Glossary – P


Pacific pygmy octopus (Octopus digueti): a small octopus native to the coasts of California and Baja California.

Pacific Ring of Fire: a seismic belt of geological hot spots that runs from north of New Zealand up through Indonesia, Japan, and the Aleutian Islands, then down the west coast of the Americas, ending in Southern Chile.

Pacific yew (tree) (Taxus brevifolia): a conifer native to the Pacific Northwest of North America.

Pacinian corpuscle (aka Lamellar corpuscle): a skin mechanoreceptor sensitive to vibration. Contrast bulbous corpuscle.

Paenibacillus vortex: a pattern-forming, social, soil bacteria species.

Pahlavi dynasty (1925–1979): the secular ruling house of Iran, founded by Reza Shah Pahlavi, who deposed the previous Shah of Iran. In 1941, he was succeeded by his son, Mohammad Reza Shah Pahlavi, who was overthrown by an Islamic revolution in February 1979.

pain: a sensation of severe discomfort; a discomfort that provokes reaction.

pais (prokaryotic acquired immune system): an adaptive immune system used by prokaryotes, commonly known as a CRISPR/Cas system.

Pakistan: a nation created via partition from India in 1947; politically secular, though with Islam as the state religion.

Palearctic: the largest terrestrial ecozone in the world, including northern Africa and the northern portion of the Arabian Peninsula, all of Europe, and Asia north of the Himalaya foothills.

Paleo-Tethys Ocean: a tropical ocean, extant from the Late Carboniferous period into the Triassic, located where the Indian Ocean and Southern Asia are now.

paleoanthropology: the study of hominins from physical evidence. Paleoanthropology combines paleontology and anthropology.

paleoatmosphere: the atmosphere before life arose.

Paleocene (66–56 mya): the 1st of 3 epochs in the Paleogene period, after the Cretaceous–Paleogene (K–Pg) mass extinction event.

Paleocene–Eocene Thermal Maximum (petm, 55.8 mya): a period of rapid global warming.

paleodicot: the most basal angiosperms, now comprising only a few hundred species.

Paleogene (66–23 mya): the 1st of 3 periods in the Cenozoic era.

Paleolithic (2.6 mya–11,700 ya): the prehistoric cultural period of human history, beginning with the development of the most primitive stone tools, roughly 2.6 mya. The Paleolithic corresponds with the Pleistocene epoch.

paleontology: the study of prehistoric life.

paleosol (geology): soil preserved by burial.

Paleozoic (541–252.2 mya): the earliest and longest of the 3 eras of the Phanerozoic eon, beginning with the Cambrian period, and ending with the Permian.

Palestine: a geographic region in the Levant, centered in the nation of Israel.

palindrome: a word, phrase, or sentence that reads the same forward or backward. Exemplary palindrome words include civic, deified, kayak, level, madam, racecar, radar, redder, refer, reviver, and rotor.

palolo: a marine worm that lives in tropical coral reefs.

palter: to act insincerely or deceitfully.

palynivore: a specialized pollen eater.

Pan American Sanitary Bureau (1902–): an international public health agency for the Americas which morphed into a regional sub-agency of the World Health Organization in 1949.

Panderichthys: a genus of extinct lobe-finned fish that arose in the late Devonian, from which tetrapods arose.

Panagrolaimus davidi: an Antarctic nematode, known to bear the horrid chill if well fed and not too old.

Panama Flow: a surface ocean current that flows southwestward from the Central American coast.

pancreas: a glandular organ that participates in the digestive and endocrine systems of vertebrates. As a digestive organ, the pancreas facilitates digestion via the release of enzymes that help break down foodstuffs and absorb nutrients in the small intestine. As an endocrine gland, the pancreas produces several important hormones, including glucagon, which raises blood sugar level, and insulin, which regulates carbohydrate and fat metabolism. See alpha cell, beta cell.

pancreatic juice: an enzyme-laden liquid secreted by the pancreas that aids digestion. Pancreatic juice is alkaline, and so useful in neutralizing acidic gastric acid.

pancrustacea: the clade comprising crustaceans and hexapods.

pandoravirus: a virus with relatively large size and genome: typically, over 2,000 genes (over 2 million base pairs). Oddly, considering their size, pandoraviruses lack the gene for the capsid protein.

panethnic: a people of multiple ethnic origins.

Pangea (aka Pangaea): the supercontinent that contained most of Earth’s land mass 300–200 mya. The global ocean of the time was Panthalassa. Pangea broke up into Laurasia to the north and the southern Gondwana.

pangenesis: an ancient hypothesis of holistic heredity via an atomic biological mechanism. Charles Darwin proposed a pangenesis in which each part of a body continually emitted gemmules, which were tiny organic particles that aggregated in the gonads, contributing heritable information to gametes.

pangolin: a nocturnal mammal with large scales covering its skin. Pangolins spend most of the day sleeping, curled up in a ball. Pangolins live in tropical regions throughout Africa and Asia. Different pangolin species in trees or on the ground. Pangolins are good swimmers. Pangolins lack teeth, and the ability to chew. They use their exceptionally long tongue to snag termites and ants from mounds or anthills torn open with their powerful font claws. Pangolins have glands that lubricate their tongues with sticky saliva; the better for their snatch-and-snack lifestyle.

panic (finance): a consequential conniption by investors.

Panic of 1857: a US financial panic from an over-expanded domestic economy and declining international trade.

Pannotia (610–550 mya): the largely southern supercontinent that broke into 4 major landmasses.

panpsychism: the idea that a consciousness and mind is inherent in all things. Panpsychism is one of the oldest philosophical theories and was the prevailing orthodoxy until the mid-20th century, when supplanted by neopositivism. Compare hylozoism, animism.

panspermia: life delivered to Earth from space.

Panthalassa: the global ocean that surrounded Pangea.

pantheism: the belief that Nature includes an immanent God. Pantheism was popularized by Spinoza. Compare supremism.

papain: an enzyme found in papaya fruit. Papain breaks peptide bonds, and so aids digestion.

Papal Schism (aka Western Schism) (1378–1417): a political discord in the Catholic church, whereupon several men simultaneously claimed to be the pope.

papalism: the papal system.

papalist: a supporter of papalism.

paper wasp: a wasp in the Polistes genus that makes its nest out of thin, paper-like sheets. The North American paper wasp (P. metricus) does so alone. In contrast, the golden paper wasp (P. fuscatus) creates a communal nest with other females. See polistine.

papilla (plural: papillae): a nipple-like structure.

pappus (plural: pappi): a tuft-like appendage to the achene of certain plants.

para-water: an isomer of water with asymmetric wavefunctions and atomic nuclear spins summing to 0. Contrast ortho-water.

parabola (algebra): a graph of a quadratic equation.

parachute plant (aka fountain flower, umbrella plant, Ceropegia sandersonii): a flowering plant native to Mozambique, South Africa, and Swaziland.

paracosm: a detailed imaginary world.

paracrine signaling: intercellular communication over a short distance. Compare juxtacrine signaling and endocrine signaling.

paradigm: a construed pattern, often used as a framework for perception.

paradox: a statement which appears self-contradictory or absurd, but which may express an insight.

Paradoxides: a genus of relatively gigantic trilobites found throughout the world during the mid-Cambrian.

paragenital: a pseudo-genital.

paraheliotropism: plant leaf movement to minimize exposure to sunlight.

parallel evolution: selfsame trait evolution in organisms of distinct clades where an antecedent similarity can be established genomically. Compare convergent evolution.

parallel postulate: Euclid’s geometric 5th postulate, which states (for 2D geometry): if a line segment intersects 2 straight lines forming 2 interior angles on the same side that sum to less than 2 right angles, then the 2 lines, if extended indefinitely, meet on that side on which the angles sum to less than 2 right angles. Unlike Euclid’s other 4 postulates, the 5th postulate was not self-evident, as attested by efforts through the centuries to prove it.

parallel universes: see many-worlds interpretation.

parallelism (evolutionary biology): adaptation that reveals itself over time; alternately, environmental tolerances that characterize generalism.

paramecium (plural: paramecia): a unicellular ciliate, widespread in all watery habitats, including brackish water. Paramecia were among the first ciliates seen by early microscopists in the late 17th century. Their easy cultivation led to being widely studied.

parameter (statistics): a quantitative characteristic of a population. Compare statistic.

páramo: an alpine tundra ecosystem in the northern Andes mountains; possibly the fastest evolutionary ecosystem in the world.

paramutation: an allele causing a heritable change in expression of a homologous allele. Paramutation results in an epigenetic state that is inherited meiotically as well as mitotically. Paramutation is common in plants but rare in animals.

paranoia: an abiding sense of peril. See persecution complex.

paranormal: not explainable via matterism.

Paranthropus (2.7–1.2 mya): a genus of robust, bipedal hominid, with considerable sexual dimorphism, and a brain similarly sized to modern chimpanzees. Paranthropus had a precision grip.

parapatric speciation: speciation by preference, of populations in nearby habitats which are not physically separated. Compare sympatric speciation and allopatric speciation.

parapatry: a relationship between organism populations with adjacent ranges with little (but some) overlap. Compare allopatry, sympatry.

paraphyletic: a taxonomic group that does not include all descendants of a common ancestor.

paraquat ([(C6H7N)2]Cl2): a toxic organic compound classified as a viologen because of its ability to reversibly change color upon reduction and oxidation.

parasite: an organism living in, on, or with another organism, obtaining benefits that usually reduces the fitness or health of its host.

parasitoid: an organism that spends a large part of its life in a parasitic relationship with a host. Unlike a true parasite, a parasitoid ultimately sterilizes or kills its host, and sometimes consumes it.

parasociality: animals of the same generation living together cooperatively in a single dwelling.

parasympathetic nervous system: the part of the autonomic nervous system associated with regulating organs and glands. See sympathetic nervous system and enteric nervous system.

Paratarsotomus macropalpis: a 0.5-mm mite endemic to southern California.

parathormone (aka parathyroid hormone, parathyrin): a hormone secreted by parathyroid glands that is instrumental in bone metabolism.

parathyroid: a vertebrate endocrine gland. Humans usually have 4 parathyroid glands, located on the back of the thyroid. The parathyroid glands affect the amount of calcium in the blood and bones.

PARC (1970–): Xerox’s Palo Alto Research Center (1970–2002) which was spun off into an independent company in 2002.

pareidolia: imagining a visual pattern where none exists.

parenchyma (botany): the most common and versatile ground tissue in plants, composed of thin-walled cells able to divide.

parent cell: a cell dividing into 2 daughter cells as the result of cellular division (replication).

Paridae: a family of small passerines that includes chickadees, tits, and titmice; endemic to Africa and the northern hemisphere.

parietal lobe: one of the 4 major lobes of the cerebral cortex in the mammalian brains. The parietal lobe integrates sensory information. See frontal lobe, temporal lobe, occipital lobe.

parity: a representation of a physical system capable of spatial transformation, transforming the system into its mirror image (parity inversion); a property of a symmetrical physical model.

parity transformation: an inversion of a spatial coordinate system. Also termed parity inversion.

Parkinson’s disease: a degenerative disease affecting the intelligence system. The most obvious early symptoms affect movement: shaking, rigidity, slowness, and difficulty walking. Later symptoms include cognitive and behavioral problems. Named after James Parkinson, who published a report on the disease in 1817.

parrot: an uncommonly intelligent bird of 372 species in 86 genera, found in many tropical and subtropical biomes. The greatest parrot diversity is in Australasia and South America.

parsec: an astronomical length unit; about 3.26 light-years, just under 31 trillion (3.1 x 1013) kilometers.

parsley (aka garden parsley, Petroselinum crispum): a species of flowering plant native to the Mediterranean, widely used as a garnish, herb, and spice.

parthenocarpy: (a plant) producing fruit without fertilization of ovules. Plants sometimes use parthenocarpy as something of a ruse. Seedless wild parsnip fruit are preferred by certain herbivores, thus acting as a decoy defense against seed predation. Other plants produce extra fruit without seeds to keep seed-dispersing animals from starvation or migration.

parthenogenesis: asexual reproduction without fertilization. From the Greek for “virgin birth.” Contrast heterogamy. { Spokes 1 }

parthenogenesis: asexual reproduction where an unfertilized egg cell nonetheless develops into an embryo. Sperm or pollen may trigger embryonic development without making a genetic contribution. In animals, parthenogenesis means an embryo developing from an unfertilized egg. From the Greek for “virgin birth.” Contrast heterogamy. See gynogenesis.

Parthian Empire (aka Arsacid Empire) (247 BCE–224 ce): a west-Asian empire in ancient Iran and Iraq.

particle (physics): a point in spacetime, typically used to ascribe a quantum-sized field. Contrast wave.

particulate radiation: radiation comprising high-speed particles.

parturition: expulsion of a newborn from the birth canal. Also called birth.

parvovirus: a rugged, genomically-compact, single-strand DNA virus in the family Parvoviridae, of 13 genera with over 75 species. Parvoviruses are categorized into 2 subfamilies: one which infects vertebrates (Parvovirinae), the other invertebrates (Densovirinae).

pascal (Pa): the SI unit of pressure, stress, and tensile strength; a measure of force per unit area; named after Blaise Pascal.

Pascal (software): a structured programming language developed by Niklaus Wirth 1968–1969.

Pascal’s principle (aka Pascal’s law, principle of transmission of fluid-pressure): a principle that pressure change to a fluid in a closed container transmits equally throughout the fluid and to the wall of the container; enunciated by Blaise Pascal in 1647–1648.

passenger pigeon (aka wild pigeon, Ectopistes migratorius): a migratory pigeon, once found in deciduous forests across most of North America east of the Rocky Mountains; hunted to extinction by humans in the last half of the 19th century.

passerine (bird): a bird in the Passeriformes order, comprising over half of all bird species (over 5,000 identified species in over 110 families). One of the most diverse terrestrial vertebrate orders, around twice that of the large mammal order: rodents. Passerines include most perching birds, such as sparrows, wrens, finches, tits, and corvids. Birds that sing are passerine.

passion: intense emotional attachment.

passive margin: a transition area between oceanic and continental crust, absent an active plate margin. Contrast active margin.

patas monkey (aka Wadi monkey, Hussar monkey): a ground-dwelling monkey native to semiarid areas of equatorial Africa.

pathogen: an infectious agent, commonly called a germ; a microorganism that causes diseases in its host, including certain viruses, bacteria, fungi, and prions.

pathological (psychology): a behavioral or thought pattern that is extreme, excessive, or markedly abnormal.

pathology: the study of disease and its diagnosis.

pathos: a quality evoking pity.

pathotype: one of numerous variations of pathogenic properties in a species of bacteria. See phage type, serotype.

pathway (biology): a biomechanical and/or chemical routine.

pathway (chemistry): a natural sequence of chemical reactions.

patriarchy: a social organization where males are dominant. Contrast matriarchy.

patrilocal: the custom of a female going to live with her husband’s family.

patrilocality: a social system where mates live in the male’s natal community.

Patriot Act (2001): a US law granting the government broad authoritarian powers to combat terrorism and surveil anyone.

patriotism: passion for one’s own country. See nationalism.

Pauli exclusion principle: a theoretical requirement that 2 fermions cannot occupy the same space simultaneously; formulated by Wolfgang Pauli in 1925.

pavement ant (Tetramorium caespitum): an aggressive, caste-based, eusocial ant 2.5–4 mm long, native to Europe but brought to America in the 18th century. Named for their ingenuity in being able to make a home in inhospitable urban environments. Considered a household pest.

Pax Britannica (Latin for British Peace) (1815–1914): the century of relative peace in Europe during which the British Empire became the global hegemonic power and adopted the pose of global police force.

PCB (polychlorinated biphenyl (C12H10-xClx)): a synthetic, organic chlorine compound derived from biphenyl ((C6H5)2), which is a molecule composed of 2 benzene rings. PCBs have been a known carcinogen since the mid-1930s. PCBs are also a neurotoxin and endocrine disrupter. PCB was used in dielectric and coolant fluids until banned in the US in 1979 and internationally in 2001.

pea: the small spherical seed of the pod fruit of the pea plant (Pisum sativum), an annual plant.

Peace of Westphalia (1648): a series of peace treaties between May and October 1648, involving Holy Roman Emperor Ferdinand III of the House of Habsburg, the Princes of the Holy Roman Empire, sovereigns of the free imperial cities, the Kingdom of France, the Swedish Empire, the Kingdom of Spain, and the Dutch Republic. The Peace of Westphalia introduced the concept of a sovereign state governed by a ruler and established a prejudice against interfering in another nation’s domestic commerce.

peach: the fruit of the deciduous tree Prunus persica, native to northwest China, in the same genus as cherry and plum. Peaches and nectarines are the same species: the difference a mere matter of fuzz on the skin.

peach-potato aphid (aka green peach aphid, Myzus persicae): a small green aphid that is a pest of peach trees, and acts as a transport vector for plant viruses that infect potatoes.

peacock: a male peafowl, known for its iridescent blue and green plumage.

peacock spider: a jumping spider which owes its name to males’ colorful, iridescent abdomen patterns which are employed in courtship displays.

peafowl: a female bird in 1 of 3 species in the Pavo or Afropavo genera. Male peafowls are commonly called peacocks. The Indian peafowl is native to the Indian subcontinent, the green peafowl of Southeast Asia, and the Congo peafowl endemic to the Congo Basin of central Africa.

peanut (aka groundnut, goober, Arachis hypogaea): a highly nutritious legume.

peasant: a lower-class free person that farms or is a hired laborer. Compare serf.

peat: an accumulation of partly decayed vegetation and other organic matter that becomes part of the soil. Areas rich in peat are called peatlands, bogs, mires, moors, or muskegs.

pectin: a polysaccharide in plant cell walls that allows growth.

pedagogy: teaching.

pedology: the study of soil.

pedoscope: a shoe-fitting X-ray fluoroscope.

pedosphere: the outermost terrestrial layer of Earth, comprising soil. Compare geosphere.

peer group: a primary group of people with similar interests, age, background, and social status. Such peers exert conformity pressure (peer pressure) on each other. See homophily.

pelagic (zone): a zone in a body of water that is neither near the shore nor close to the bottom (benthic).

pellagra: a niacin-deficiency disease that is characterized by skin changes, diarrhea, and intelligence system dysfunction.

Peloponnesian War (431–404 BCE): the war between Athens and its empire against the Peloponnesian League, which was a confederation in southern Greece led by Sparta.

pelycosaur: an informal grouping of basal synapsids.

pemphigus: a rare autoimmune disease that affects the skin and mucus membranes, creating horrendous ulcers.

penguin: a flightless seabird of 17–20 species, living in the southern hemisphere, commonly Antarctica. While many are found in cold climates, several species live in the temperate zone.

penicillin: an antibiotic derived from Penicillium fungi.

penis: the sex organ that males employ to inseminate females via copulation. See vagina.

penis envy (Freudian psychoanalytic theory): a girl’s envious reaction to realizing that she lacks a penis (even as Freud considered the clitoris a female’s penis). Penis envy is different from small penis syndrome, which is a male suffering angst by thinking that his dick is dinky, a notion explored by Otto Fenichel.

pennaceous feather: a feather type found in modern birds and some maniraptoriform dinosaurs, comprising a stalk or quill (rachis) with feathered vanes (vexilla) to either side.

pension fund (aka superannuation fund): a fund which provides retirement income. Pension funds are major investors, and are especially important to stock markets, where large institutional investors dominate. Pension funds worldwide collectively held $39.6 trillion US in assets in 2015.

penury: severe poverty.

pepo: a berry with many seeds, a tough outer skin or rind, but not internally divided by septa (membranes).

pepper (Piper nigrum): the plant that renders green, white, and black varieties of the spice known as pepper.

peppered moth (Biston betularia): a nocturnal moth that adapts its shading to its resting surface environment.

pepsin: an enzyme released in the stomach that degrades food proteins into peptides.

peptide: a short chain of amino acids: 2 to 50 or so. A longer chain is properly termed a protein.

peptide bond (aka amide bond): a covalent chemical bond, usually between amino acids.

peptidoglycan (aka murein): a polymer comprising sugars and amino acids, forming a mesh-like layer outside a cell’s plasma membrane.

peramorphosis: an evolutionary change in developmental rates that adds new stages to those in ancestors; typically, extended growth periods.

perceive, perception: mentally integrating sensory input (sensation) using memory. Perception is a 3-stage process: 1) turn a sensation into a symbolic representation, 2) identify sensed symbols using memory and categorization, then 3) derive the meaning of the identified symbols, especially regarding affinity or avoidance. See conceptualization.

perching bird: an arboreal passerine.

Perciformes (aka Percomorpha, Acanthopteri): a class of ray-finned fish; the most numerous order of vertebrates, comprising 41% of all bony fish. Perciformes means “perch-like.”

perennate: persist; be perennial.

perennial (botany): a plant that is present aboveground throughout the year, and which lives for more than 2 years. Woody plants, such as shrubs and trees, are perennials. Compare annual, biennial. See herbaceous.

perfect pitch (aka absolute pitch): being able to identify a note upon hearing it.

pergenome: the personal genome of a cell in a multicellular eukaryote, as contrasted to the genome of the organism.

pericarp: the layers of a ripened ovary or fruit, typically comprising 3 layers: exocarp, mesocarp, and endocarp.

periderm: the secondary covering on small woody stems and non-woody plants.

peridotite: coarsely granular igneous rock, composed chiefly of olivine with an admixture of various other minerals.

perihelion: the closest point to a star of an orbiting body.

period (geology): a duration in the geological time scale, roughly 100 million years; shorter than an era, longer than an epoch.

periodic table of elements: a tabular display of atomic species (chemical elements), presented in increasing order of their atomic number (number of protons), with columns (groups) and rows (periods) based upon electron configuration.

peripheral nervous system: the part of the nervous system excluding the brain and spinal cord.

peripheral vision: vision in animals with 2 eyes that occurs outside focal gaze. See binocular vision.

perissodactyl: an odd-toed, nonruminant, ungulate mammal in the Perissodactyla order.

peristalsis: waves of involuntary muscle contractions along the walls of a hollow muscular structure, such as the esophagus, stomach, or intestine, forcing the contents within onward.

permafrost: perennially frozen soil. Most permafrost is in the high latitudes (polar regions), but also occurs in high mountain ranges (alpine permafrost).

Permanent Court of Arbitration (1989–): a supranational arbitral tribunal.

permeable: a membrane that has pores through which molecules may pass.

Permian (299–252 mya): the 6th and last period of the Paleozoic era, following the Carboniferous period and preceding the Triassic. The name derives from the ancient Russian kingdom of Permia. Earth at the time had a single supercontinent: Pangea, surrounded by the global ocean Panthalassa. The extensive rainforests of the Carboniferous were gone, leaving vast regions of arid desert in the continental interior. Reptiles, better adapted to dryer conditions, rose to dominance over their amphibian ancestors.

permittivity (electromagnetism) (aka absolute permittivity): the measure of charge (capacitance) when forming an electric field in a certain medium.

persecution delusion: paranoia about someone or others.

“Just because you’re paranoid doesn’t mean they aren’t after you.” ~ Joseph Heller

Persia (the Achaemenid Empire; 1st Persian Empire): an ancient empire in west and southwest Asia founded by Cyrus the Great, with its greatest extent 550–330 BCE. There were 2 other ancient Persian empires, Parthian (247 BCE–224 ce) and Sasanian (224–651), but reference herein is to the 1st Persian Empire.

personal fact: a personally experienced fact. See fact. Contrast social fact.

personality: individual patterns of behavior in an organism that suggest a certain emotional orientation or worldview.

perovskite: see bridgmanite.

persistence of vision: the optical illusion that a visual perception briefly lingers after its disappearance.

personality: individual patterns of behavior in an organism that suggest a certain emotional orientation and/or worldview.

perspective-ignorance: see pignorance.

perspective-taking: the process of perceiving an event from another’s point of view.

pessimism: an opinion of negativity about a certain system. Contrast optimism.

perturbation theory: mathematical methods to squeeze an approximate answer from equations that refuse to resolve to an exact solution.

pest: an organism deemed a nuisance.

pesticide: a biocide intended to destroy pests.

PET: see positron emission tomography.

PETA (People for the Ethical Treatment of Animals): a non-profit organization that works against animal suffering, particularly targeting factory farms, the clothing trade, laboratories, and the entertainment industry.

petal: a modified leaf that surrounds the reproductive parts of a flower.

Peter principle: a 1969 tongue-in-cheek proposal by Laurence Peter that, within bureaucracies, managers are promoted until they are incompetent at their position.

petiole (botany) (aka leafstalk): the stalk that attaches a leaf to a stem.

petrel: a tube-nosed seabird.

petroleum: a natural yellow-to-black liquid comprising algae, zooplankton, and other organisms crushed, heated, and liquefied. Compare coal, natural gas.

pH: a measure of acidity which ultimately relates to the number of protons in a solution. 7 = neutral; < = acidic; > = base (alkaline).

phage type: one of numerous variations of susceptibility to viruses in a species of bacteria. See pathotype, serotype.

phagocyte: an animal cell which protects it host body by ingesting harmful foreign particles, select microbes, and dying or dead cells.

phagocytosis: the process of engulfing and ingesting cellular material; a form of endocytosis.

phagophore: a membrane-enclosed vesicle created during the initial stage of autophagosome formation.

phagotroph: a heterotrophic protist that eats via phagocytosis.

phalarope: a slender-necked shorebird of 3 species in the genus Phalaropus.

Phanerozoic (542 mya–now): the 4th geological eon, characterized by complex life inhabiting Earth (based upon an outdated assessment), beginning with the Cambrian period.

phantom limb syndrome: the animal sensation that a missing body part is still attached. Phantom sensations are experienced in many body parts, including lost eyes and extracted teeth.

pharynx: the passageway tube in the throat that is used for both breathing and eating. The pharynx is also instrumental in vocalization.

phase (physics, chemistry): a physically distinctive form of matter. Common phases, corresponding to temperature/energy levels, are gas, liquid, plasma, and solid.

phase transition: change from one operational state, or state of matter, to another.

Pheidole: an ant genus with over 1,000 species. Pheidole tend to be an ecologically dominant species.

Pheidole pallidula: a Mediterranean and north African ant.

phenol (C6H5OH; aka carbolic acid): a mildly acidic, volatile, aromatic, organic compound, which is a white crystalline solid. A phenol comprises a phenyl group (C6H5) bonded to a hydroxyl group (OH).

phenology: biological phenomena that correlate with climatic conditions.

phenomenal: known through perception. Contrast intuition.

phenomenon (plural: phenomena): a perceptible event. See actuality. Contrast noumenon.

phenomenology (philosophy): the study of the nature of phenomena, experience, and consciousness. See ontology.

phenomenology (psychology): the study of subjective experience.

phenotype: the composite visible traits of an organism: physical, physiological, and behavioral. Compare mentotype.

phenylalanine (Phe; C6H5CH2CH(NH2)COOH): an electrically-neutral amino acid used to form proteins.

phenotypic plasticity: the ability of an organism to alter its body to suit current conditions.

pheromone: a secreted or excreted hormone employed as a communication signal.

phi phenomenon: the optical illusion of perceiving continuous motion when shown a rapidly-presented series of still (static) images. Moving pictures illustrate the phi phenomenon. Compare beta movement.

Philippines: an archipelagic country in Oceania comprising ~7,641 islands, run as a republic, with a presidential system similar to the United States.

philology: the study of language from written historical sources.

philopatry: the tendency of an organism to stay or habitually return to a certain area. Natal homing – an animal returning to its birthplace to breed – is a common philopatry.

philosopher’s stone: legendary alchemical substance capable of turning base metals into precious metals (gold or silver).

philosophical pessimism: a worldview that finds the unsavory facts of the world the source of psychic suffering. Philosophical pessimism is a philosophic admission of defeat by the pignorant.

“Time is a burden; the course of history is in some sense ironic; freedom and happiness are incompatible; and human existence is absurd.” ~ Joshua Dienstag

philosophy: a set of consistent definitions pertaining to a system which yields a hierarchical construal. The term philosophy derives from the ancient Greek for “love of wisdom.” There are 3 branches of philosophy: natural, moral, and metaphysical. Natural philosophy, which evolved into science, concerns Nature. Moral philosophy deals with the principles of ethics. Metaphysics considers first principles, such as ontology, and is intimately connected with epistemology.

phloem: tissue that distributes sugar-laden sap among a plant. Compare xylem.

phlogiston theory: the notion of fire as an element.

Phoenicia (2500–539 BCE): an ancient civilization of city-states (like ancient Greece) that originated on the western, coastal part of the Fertile Crescent.

phobia: persistent fear of a specific activity, situation, or object.

phoneme: a unit of sound in speech.

phonics: a method of teaching reading via learning the phonetics of letters and syllables.

phonology: the study of language sounds; a subdiscipline of linguistics.

phonon: a collective excitation of interacting quanta, characterized by a vibrational mode.

phoresy (aka phoresis): a commensalism where the symbiont is transported by the host.

phorid fly (aka scuttle fly): a family of tiny humpbacked flies that resemble fruit flies. Many are specialist parasitoids of ants and stingless bees.

Phormidium frigidum: a psychrophilic cyanobacterium native to Antarctica.

phosphate (PO43-): a soil-bound mineral nutritionally needed by plants.

phosphine (PH3): a colorless, flammable, toxic gas.

phospholipid: a class of lipids that are a major component of cell membranes, as they can form bilayers which afford regulated communication flow. The first phospholipid identified was lecithin, found in the egg yolk of chickens by Theodore Gobley in 1847.

phosphoric acid (H3PO4): a corrosive acid.

phosphorus (P): the element with atomic number 15; as a mineral, always maximally oxidized. A component of RNA, DNA, ATP, and other biocompounds, phosphorus is essential to life.

phosphorous oxychloride (POCl3): a colorless liquid that hydrolyzes in moist air, releasing phosphoric acid and choking fumes of hydrogen chloride.

phosphoryl group (P+O32–): a radical of phosphorous of oxygen.

phosphorylation: attaching a phosphoryl group (PO32–) to a molecule. Phosphorylation and dephosphorylation are extensively employed in cellular processes. In eukaryotes, protein phosphorylation is an extremely common genetic post-translational modification. The addition of a phosphate group to a protein that can alter gene expression by altering the proteins involved in building other proteins. Contrast dephosphorylation.

photobiont: an autotrophic photosynthetic symbiont.

photobleaching (aka fading): photochemical alteration of a pigment molecule such that it cannot fluoresce (emit light).

photochemistry: the branch of chemistry about the chemical effects of light.

photoelectric effect: a body’s emission of charged particles (photoelectrons or ions) upon absorbing electromagnetic radiation.

photoelectron: an electron emitted from an object via the photoelectric effect.

photoisomerization: the molecular behavior of changing isomer upon photoexcitation (absorbing a photon).

photolysis (aka photodissociation, photodecomposition): chemical decomposition via radiant energy.

photon: a hypothetical bosonic particle of light; more properly, a packet of light energy, as light exhibits both particulate and wave appearances. Though photons supposedly do not interact with each other, they somehow porter the force of electromagnetism.

photoperiodism: plant responses to changes in the length of days and nights.

photophore: a light-producing organ.

photophosphorylation: the phosphorylation of ADP to form ATP during photosynthesis.

photopia: vision in bright light. Contrast scotopia.

photopic vision: sight under well-light conditions. Contrast scotopic vision.

photoprotection: the biochemical process by which cells cope with molecular damage from sunlight.

photoreceptor (cell): a specialized cell capable of visual phototransduction.

Photorhabdus luminescens: a bioluminescent bacterial symbiont to entomopathogenic nematodes that helps its host by killing insects.

photosphere: the visible surface of the Sun; the layer of the Sun’s atmosphere that emanates light; the lowest (1st) of 3 main layers of the Sun’s atmosphere. The chromosphere is above the photosphere.

photosynthesis: (an organism) converting sunlight into energy.

phototransduction: the 4-step cellular process of converting light into a sensory signal. See transduction.

phototroph: an organism that can turn light energy into metabolic chemical energy.

phototropin: a photoreceptive protein sensitive to blue light. See chlorophyll, cryptochrome, neochrome, phytochrome.

phototropism: a natural tendency for light to be an orienting stimulus.

phrenology: the pseudoscience that measurements of the skull could reveal a person’s psychology, because the brain was the organ of the mind.

phycodnavirus: a large double-stranded DNA virus that infects marine or freshwater eukaryotic algae.

phycotoxin: an allelopathic compound produced by prokaryotic and eukaryotic algae.

phylesis: the course of phylogenetic development.

phyletic gradualism: the Darwinian notion of gradual (over millions of years) descent by modification via “natural selection.”

phyllotaxy (aka phyllotaxis): the arrangement of leaves on a plant stem.

phylogenetics: the study of biological evolutionary history via genetic analysis.

phylogeny (evolutionary biology): the evolution of a genetically related group of organisms.

phylum (biological classification) (plural: phyla): the taxon above class and below kingdom. Phylum typically refers to a uniquely identifiable body plan. Ernst Haeckel coined phylum in 1866. See family.

Physarum: a genus of slime molds.

physical chemistry (aka physiochemistry): the study of particulate phenomena in chemical systems; in other words, the study of physics in chemistry.

physical model: a typically geometric or algebraic mathematical model yielding a mathematical description of the embodied phenomena.

physical property: any measurable property of a physical system.

physical quantity: a measure of a physical property.

physical system: a portion of a physical universe chosen for examination. Everything outside the system is its environment.

physical theory: an explanation of relationships between various measurable phenomena. A physical theory may include a model of physical events (i.e., a physical model).

physics: the natural science of matter and its patterns of motion, with the intent of understanding how the universe behaves.

physiochemistry: see physical chemistry.

physiocracy: construing political and/or economic systems as a natural order.

physiognomy: the assessment of a person’s personality based upon features of facial structure.

physiological psychology: the empiricist view of psychology as an adjunct to physiology. This school of belief culminated in behaviorism and contributed to the gumbo known as cognitive psychology.

physiology: the physical structures and biomechanics of an organism.

phytochemical: a plant-produced chemical compound.

phytochrome: a photoreceptive protein sensitive to red light and temperature which plants employ. See chlorophyll, cryptochrome, neochrome, phototropin.

phytoestrogen: a plant compound similar to estrogen.

phytohormone: a plant hormone. Phytohormones regulate plant growth.

phytonutrient: a nutrient obtained by eating plants.

phytopathogen: a plant pathogen.

Phytophthora infestans: the pathogenic fungus that causes potato blight.

phytoplankton (aka microalgae): photosynthesizing aquatic organisms, both marine and freshwater; from the Greek words for plant and drifter. Oceanic phytoplankton is the primary food source, directly or indirectly, of nearly all other marine life.

phytoplasma: specialized parasitic plant bacteria.

phytosteroid (aka plant steroid): a steroid naturally occurring in plants.

phytosterol: plant steroid compounds similar to animal cholesterol.

phyotosynthate: a product of photosynthesis.

pi bond: a covalent bond formed by overlapping atomic orbital lobes. Compare sigma bond.

picogram: 1-trillionth (10–12) of a gram.

picosecond: 1-trillionth (10–12) of a second.

Picrophilus oshimae: an acidophilic species of archaea.

pictogram (aka pictograph): a written symbol representing an object. Compare ideogram.

pied flycatcher (Ficedula hypoleuca): a small, migratory European passerine which practices polygyny.

pied wagtail (aka water wagtail, Motacilla alba yarrellii): a small, slender passerine with a long, constantly wagging tail; native to the British Isles.

Pierolapithecus: a hominoid that lived 11.9 mya.

piezoelectric: the property of some nonconducting crystals to become electrically polarized when mechanically strained and, conversely, becoming mechanically strained when an electric field is applied.

piezophile: an organism that lives at a high hydrostatic pressure, such as in an ocean trench.

pig: an even-toed ungulate in the Sus genus.

pigeon: a stout-bodied bird with a short, slender bill; in the clade Columbidae with doves.

pignorance (perspective-ignorance): a wrong worldview from not knowing the nature of existence. Compare fignorance. See ignorance, naïve realism.

pike: a freshwater fish in the Esox genus, with 6 extant species.

pillbug (aka roly polies, doodle bugs): an insect which can roll up into a ball; in the same family (Armadillidiidae) with woodlice.

Pilobolus: a genus of fungi that lives on herbivore excrement.

pilot wave theory: the deterministic theory that there is an inherent wave/particle duality for every elementary particle; proposed by Louis de Broglie in 1927. Contrast uncertainty principle.

pilot whale: a dolphin in the genus Globicephala, with 2 species: short-finned (G. macrorhynchus) and long-finned (G. melas).

pilus (aka fimbria; plural: pili, fimbriae): a hair-like appendage found on bacteria. Pili serve various purposes, from motility to conjugation (DNA transfer).

pinna: a leaflet, or projecting animal body part.

pine: a softwood conifer native to the northern hemisphere, with ~115 species in the Pinaceae genus.

pineal gland: a small endocrine gland in the vertebrate brain which produces melatonin.

pineapple (Ananas comosus): a fruiting tropical bromeliad.

pink (salmon): the smallest and most abundant species of Pacific salmon. These cold-water fish (5.6–14.6 °C, optimally 10.1 °C; upper incipient lethal temperature = 26 °C) live 2 years. Pink salmon traditionally range from Arctic coastal waters to the Sacramento river in northern California. Pink salmon have been a mainstay of commercial harvesting. As such, they are critically imperiled from California through Washington, but, as of 2012, faring well enough in British Columbia and Alaska.

pinna: a leaflet, or projecting animal body part.

pinnate: a biological arrangement of having similar parts on opposite sides of an axis, as with barbs on the rachis of a feather, and with compound leaves.

pinniped: a diverse group of fin-footed marine mammals, including seals, sea lions, and walruses. Pinnipeds are typically sleek-bodied and barrel-shaped: bodies admirably adapted for an aquatic lifestyle.

Pinocchio: the protagonist of the children’s novel The Adventures of Pinocchio (1883) by the Italian author Carlo Collodi. Pinocchio was a wooden puppet that dreamt of becoming a real boy. Pinocchio was prone to fabricating stories and telling lies for various reasons.

pinnule: a bodily part or organ that resembles a fin.

pioneer plants: the 1st wave of plants that occupy a new soil.

pinyon jay (Gymnorhinus cyanocephalus): a western United States jay. The pinyon jay and Eurasian cousin nutcracker are an example of convergent evolution in filling a similar habitat niche.

pipefish: a subfamily of small fish that resembles a seahorse, which is in the same family.

piperonal (C8H6O3; aka heliotropin): an organic compound common in flavors and fragrances, including black pepper, dill, violet, and vanilla.

Piraha: an indigenous people of the Brazilian Amazon rainforest. The Piraha call themselves Hi’aiti’ihi, which loosely translates as “the straight ones.” The Piraha have no social hierarchy; there are no formal tribal leaders. Like many early societies, the Piraha are egalitarian and practice common ownership (sociality which Karl Marx called “primitive communism”).

piscivore: an animal which primarily eats fish.

pistil (aka carpel): the female part of a flower, acting as a pollen receptor.

pit viper (Crotalinae): a subfamily of vipers, endemic to Asia and the Americas, with a visible heat-sensing organ (pit).

pitch (music): the frequency of a tone.

pitcher plant: a carnivorous or saprophytic plant in the genus Nepenthes, endemic to the tropical or tropical-montane biomes of the Malay Archipelago, Southeast Asia, and the eastern part of Madagascar.

pith (botany): soft, spongy growth tissue in the center of a plant. Pith is replaced by xylem in grown stems and branches.

pithecid (Pitheciidae): a family of New World monkeys that includes titis, sakis, and uakaris.

pitohui: a passerine of 6 species, endemic to New Guinea; noted for its toxic feathers and skin, owing to its ingestion of melyrid beetles.

pituitary gland (aka hypophysis): an endocrine gland at the base of the brain, off the bottom of the hypothalamus. The pituitary gland is not a part of the brain. The human pituitary gland is the size of a pea, weighing 0.5 grams.

Pixar (1979–2006): American computer animation film studio which began as part of Lucasfilm, purchased by Disney in 2006.

placebo: a simulated medical treatment intended to inspire the recipient, thereby provoking the placebo effect of working to relieve or even cure the targeted affliction. The term placebo originated with an old Latin word for “I shall please.” In medieval times, a placebo opened the Catholic Vespers for the Dead, which were sung by hired mourners for a funeral; sycophants who wept crocodile tears on behalf of the family. This gave placebo the odious meaning of a toady. The term took its medical context in the early 19th century, when placebos were remorsefully employed. Placebos’ efficacy gradually transformed their moral worth. { Spokes 5, 8 }

placebo: a simulated medical treatment intended to inspire the recipient, thereby provoking the placebo effect of working to relieve or even cure the targeted affliction. The placebo effect illustrates the powerful sway that the mind has over health. { Spokes 1, 4 }

placebo effect: a rejuvenation owing solely to mental invigoration via belief in a placebo (totemic treatment).

placenta: an organ that connects a developing fetus to the uterine wall of its mother. Placentas are found in certain mammals, including humans, and some snakes and lizards.

placoderm: an early, armored, jawed fish that evolved early in the Silurian.

placozoa: a basal invertebrate, 1 mm across.

Planck constant (aka Planck’s constant, Plank’s action quantum): a physical constant reflecting the size of energy quanta in quantum field theory. Planck’s constant states the proportionality between the momentum and quantum wavelength of every subatomic particle. The relation between the energy and frequency of quanta is the Planck relation.

Planck length: the minimal theoretical limit to spatial distance; a measure derived from Newton’s gravitational constant, the speed of light in a vacuum (c), and Planck’s constant. Planck length is 1.616199 x 10–35 meters.

Planck mass: the theoretical amount of mass in a sphere with a radius Planck length, with a density of 1093 g/cm3.

Planck satellite: a space probe launched in 2009 by a European consortium to measure cosmic radiative energy.

Planck time: the theoretical limit of temporal measurement; the time required for light in a vacuum to travel a single Planck length. At 5.391 x 10–44 seconds, Planck time is the shortest sprint imaginable.

Planck unit: a system of natural units used in physics, particularly Planck length and Planck time.

planetary nebula: a cloud of ionized gas emitted by a star toward the end of its life.

plankton: a minute organism living in a water column (freshwater or salt) that is incapable of swimming against a current. The term plankton is both singular and plural (they’re just too damn tiny to count).

plant: a kingdom of eukaryotic autotrophs, including mosses, ferns, conifers, and flowering plants (angiosperms).

plantain (Plantaginaceae): a diverse, cosmopolitan family of flowering plants, occurring mostly in temperate climates.

planthopper: a tiny hopping insect in the Issus genus that lives on vegetation, both residentially and dietarily. Planthoppers feed on phloem.

planum temporale: a cortical area in the middle of the brain on both sides.

plasma: an ionized gas; one of the 4 fundamental states of matter, the others being gas, liquid, and solid.

plasma membrane: the membrane holding a cell’s cytoplasm and other contents within.

plasmid: a DNA globule, useful to microbes for horizontal gene transfer (swapping genetic material).

plasmodesma (plural: plasmodesmata): a microscopic channel traversing the cell walls of plant cells, and some algae cells, enabling communication and transport between cells.

Plasmodium: a genus of parasitic protozoa. Infection of Plasmodium falcipanum is known as malaria. Compare plasmodium.

plasmodium: an ameboid which congregates to form a slime mold. Compare Plasmodium.

plasmon: a quantum of plasma oscillation.

plastid: a catchall term for the organelles in plants and algae, including those responsible for photosynthesis.

platelet: a minute, flattened body.

platypus (aka duck-billed platypus, Ornithorhynchus anatinus): a semiaquatic mammal endemic to eastern Australia. Platypus are monotremes. The platypus is one of the few venomous mammals. Males have a spur on their hind foot that delivers a painful incentive to bugger off.

Platyrrhine (aka New World monkeys): a group of New World monkeys. Compare cercopithecid.

play: entertaining recreational activity.

Plaza Accord (aka Plaza Agreement): an agreement signed at the Plaza Hotel in New York City on 22 September 1985 among the governments of the United States, Britain, France, West Germany, and Japan, to intervene in currency markets to depreciate the US dollar. The Plaza Accord was Reagan’s response to the prospect of protectionist measures by Congress on behalf of US manufacturers.

pleasure principle: a Freudian term for the idea that people instinctually seek pleasure and avoid pain to satisfy needs. Freud specifically thought that the pleasure principle drives the id.

plenary (politics): attended by all members.

pleomorphism: (an organism) able to change shape or size in response to environmental conditions.

pleiotropy: a single gene influencing multiple seemingly unrelated traits.

Pleistocene (2.588 mya–11,700 ya): the epoch that follows the Pliocene and precedes the Holocene; defined by Charles Lyell for the emergence of modern marine mollusks. The Pleistocene ends with passing of the Younger Dryas cold spell.

Plesiosauria (200 – 66 mya): a clade of sauropterygians.

Pleurodira: a minority suborder of the turtles. Pleurodires are side-necked turtles that must bend their neck muscles horizontally to pull their necks back toward their shell, as contrasted to cryptodires (hidden-neck turtles), which may pull their heads straight back into their shells. Pleurodirans are endemic to freshwater environs in the southern hemisphere: South America, Africa, and Australia. Contrast Cryptodira.

Pliobates: a hominoid that lived 11.6 mya.

Pliocene (5.332–2.588 mya) (aka Pleiocene): the 2nd and last epoch in the Neogene, following the Miocene and preceding the Pleistocene. From the Greek for “continuation of the recent.” Oddly defined by Charles Lyell as being the most recent fossil rock layer.

ploidy: the set count of chromosomes in a biological cell. Many prokaryotes are haploid (1 set). Most eukaryotes, including most animals, are diploid (2 sets), though 30–80% of living plants are polyploid (> 2). Polyploidy can occur in animal tissues, such as the human liver.

plover: a wading bird in widely distributed group of 40 species.

plow (noun): an implement for cutting, lifting, and turning over soil, especially for preparing a seedbed.

plumage: the entire feathery covering of a bird.

plum: a fruit tree in the Prunus genus; one of the earliest domesticated fruits.

plume (mantle): the rising of hot rock from the core-mantle boundary through the mantle to become a diapir (intrusion) in the Earth’s crust.

pluralistic ignorance: a social phenomenon where most members of a group do not believe what they consider to be the majority outlook or belief of the group.

pluricellularity: the structure of multiple cells aggregating in an organized manner. Biofilms are pluricellular, as are bacterial filaments. Contrast multicellularity.

plutocracy: political rule by the wealthy.

pluripotency: a stem cell able to differentiate into any cell type.

Pluto: a large ice-encrusted lump on the outskirts of the solar system; once considered a full-fledged planet, but demoted in 2006 to a dwarf planet, owing to its relatively low mass. For consolation, Pluto has 4 moons.

plutocracy: social stratification controlled by the materially advantaged.

plutonium (Pu): the element with atomic number 94; a silvery-gray metal that tarnishes when oxidized, much like nickel. Plutonium is the heaviest primordial element.

pneumatic chemistry: the quaint term for research into the nature of gases; used from the 17th to early 19th century.

pneumatophore: a specialized aerial root that enables a plant to breath air in habitats with waterlogged soil. The black mangrove is differentiated from other mangrove species by its pneumatophores.

Poaceae: the angiosperm family of grasses.

pod (social): a social group; often used with marine mammals.

podophyllin: a derivative from the rhizome of the American Mayapple, once commonly used against genital warts. Podophyllin is toxic and has side effects on the skin where applied.

Pogonomyrmex: a genus of harvester ants endemic to the deserts of North and South America.

poikilohydry: an organism lacking a mechanism to prevent desiccation, as it is tolerant of large fluctuations in hydration. Lichen and bryophytes are poikilohydric.

Poincaré group: a group of isometries in a particular (Minkowski) spacetime which corresponds with special relativity. Named after Henri Poincaré.

point mutation (genetics): a mutation of a single nucleotide exchanged for another.

poison frog (aka poison-dart frog, poison arrow frog): a diurnal, poisonous frog native to Central and South America, with over 170 species. Many poison frogs have brightly colored bodies with stark patterns which advertise their toxicity (aposematism).

poison ivy: a rash caused by allergic reaction to urushiol, a sap produced by plants in the Toxicodendron genus (poison ivy, poison oak, and poison sumac).

polar bear: a carnivorous bear that lives in the Arctic Circle.

polar body: a small haploid cell formed concomitantly as an egg cell during oogenesis, but which generally cannot be fertilized.

polar coordinate system: a 2D (planar) coordinate system in which a point can be specified as at a distance from a fixed point (typically the origin (0,0)) and an angle from a fixed direction (typically the horizontal axis).

polar vortex: the gyre of low pressure and cold air at both of Earth’s polar regions.

polarity (chemistry): a molecule that has positive and negative poles; in other words, a molecule with an electric dipole moment. Polar molecules have polar bonds owing to a difference in electronegativity between the bonded atoms. Water is a polar molecule.

polarization (optics): a state of light in which the radiation exhibits distinct properties in different directions.

polaron: a quasiparticle of electron mobility.

polio (poliomyelitis, aka infantile paralysis): an infectious disease caused by the poliovirus, a human enterovirus.

polis (plural: poleis): an ancient Greek city-state.

polistine: a eusocial wasp in the Polistinae subfamily, which has ~1,100 species in 4 tribes. Polistines are commonly known as paper wasps, though other wasps, such as the yellow jacket, make their nests from paper. These wasps are mostly tropical or subtropical, yet some of the most frequently encountered wasps in temperate biomes are polistines.

political economy: the macroeconomic study of the economies of polities. Political economy evolved from moral philosophy, evolving in the 18th century into the study of the economic dynamics of nation-states. In the late 19th century, the term simplified to economics; an effect of the influential textbook Principles of Economics (1890) by Alfred Marshall. The term political economy is still used to specifically indicate the effects of governments on economies.

politics: theories of government and the practice of governance.

polity: a particular form of government.

pollen (botany): a mass of male microspores (microgametophytes) in a seed plant.

pollinarium (plural: pollinaria): the complete male reproductive structure transporting pollinia.

pollination: the process of transferring pollen, enabling plant fertilization and reproduction.

pollinium (plural: pollinia): a sac of pollen.

polyacetylene ((C2H2)n): an organic polymer with the repeating compound. Polyacetylene has high electrical conductivity.

polyandry: a mating system of 1 female and 2 or more males. Contrast polygyny.

polyatomic ion (aka molecular ion): an ion with 2 or more atoms covalently bonded which act as a single unit. Historically, a polyatomic icon was referred to as a radical.

polychaetes (aka Polychaeta): a class of hardy marine worms.

polychloro phenoxy phenol: a group of highly reactive (polyhalogenated) organic compounds.

polychronic (culture): a socially oriented culture that considers schedule adherence secondary to civility. Contrast monochronic .

polychlorinated biphenyl: see PCB.

polycrystal: a substance, typically a solid, comprising many fused crystallites (microscopic crystals).

polydnavirus: a double-stranded DNA virus with a symbiotic relationship with parasitoid wasps. There are 2 genera of polydnavirus, based upon infected wasp genus (ichneumonid, braconid), with at least 53 species.

polyethylene ((C2H4)n) (aka polythene): the most common plastic, with 110 million tonnes produced in 2018.

polygamy: a mating system of having multiple contemporaneous mates. See polyandry and polygyny. Contrast monogamy.

polygyny: a mating system 1 male and 2 or more females. Contrast polyandry.

polymath: a person of encyclopedic learning.

polymer: a macromolecule (large molecule) comprising repeating monomers (molecular units).

polymerization: a process of reacting monomer molecules together to form polymer chains or 3d networked structures.

polymorph: a substance that has multiple potential structures. Polymorphs are typically solids, though helium-4 is a polymorph for its liquid phase.

polymorphism: the capability to assume different forms.

polymorphism (biology): the existence of an organism with several form or color varieties.

polymorphism (object-oriented programming): the ability of different classes to overload (use the same) behavior names.

polynomial: an algebraic expression consisting of variables and coefficients, where the expression is limited to addition, subtraction, multiplication, and non-negative integer powers.

Polynucleobacter: a genus of freshwater bacteria, some of which are free-living, others as obligate endosymbionts of Euplotes ciliates.

polynucleotide: a biopolymer of 13 or more nucleotide monomers covalently bonded in a chain. DNA and RNA are polynucleotides.

polyol: an alcohol containing multiple hydroxyl groups.

polyp: an organism with a fixed base, columnar body, and an open end with mouth and tentacles.

polypeptide: a short chain of amino acid monomers, linked by peptide bonds.

polyphagy: the ability of an animal to eat a variety of food. Contrast monophagy. Compare oligophagy.

polyphenol (C6H5OH): a polymer comprising phenol.

polyphenol oxidase (aka PPO): an enzyme with various roles depending upon species. In insects, PPO provides desiccation tolerance.

polyphyletic (polyphyly): a classified group of organisms characterized by 1 or more homoplasies: traits that appear to be the same, but not inherited from a common ancestor. Endothermic animals, which includes birds and mammals, are polyphyletic. The last common ancestor of birds and mammals was ectothermic. Endothermy evolved independently in the ancestors of birds and the ancestors of mammals.

polyploidy: cells with more than 2 paired (homologous) sets of chromosomes. Polyploidy is common in ferns and angiosperms (flowering plants). Some animals, such as goldfish, salmon, and salamanders, possess polyploidy. In other animals, polyploidy may result from abnormal cell division.

polysaccharide (aka glycan): a complex sugar-based macromolecule. Starch and glycogen are polysaccharides, as are cellulose and chitin, which plants employ as structural materials. Compare monosaccharide.

polysemy: the capacity for a signification to have multiple meanings.

polysensory: able to process incoming data patterns from more than one source.

polyunsaturated: a fat molecule with more than one double carbon bond. Compare monounsaturated.

polytheism: belief in multiple gods. Contrast monotheism.

Ponerine: an ant with a stinger, with 1,600 species in 28 extant genera.

pons: the part of the brainstem that links the medulla and the thalamus.

Pontifical Academy of Sciences (1936–): the scientific academy of the Vatican City, sponsored by the Papacy of the Catholic Church.

Ponzo illusion: a visual illusion devised by Mario Ponzo in 1911: that 2 lines of identical length are perceived of different lengths when bracketed by converging lines that appear to confer linear perspective.

Pope: the worldwide leader of the Catholic Church. The primacy of the Bishop of Rome derives from his role as the traditional successor to Saint Peter, to whom Jesus mythically gave the keys of Heaven, and the powers of “binding and loosing,” naming Peter, and ostensibly his successors, as the “rock” upon which the church would be built.

popoto (aka Maui’s dolphin): the smallest dolphin; rare.

poppy: a flowering plant in the Papaveroideae subfamily of the Papaveracea family. One species is notably notorious: the opium poppy (Papaver somniferum).

Popular Mechanics (1902–): a US-based technology magazine, originally oriented toward mechanical engineering.

population (biology): conspecifics within a geographical area.

population (statistics): the set of objects about which information is wanted.

population parameter (aka statistical parameter): a numerical characteristic of a population or statistical model; a quantity that indexes a family of probability distributions. A parameter of a population is as a statistic is to a sample.

porcupine: the 3rd-largest rodent (behind the capybara and beaver), with a coat of sharp spines, indigenous to the Americas, southern Asia, and Africa. Mostly nocturnal, porcupines are herbivores.

porpoise: a small cetacean, related to dolphins and whales, of which there are 6 species. All porpoises are oceangoing. Most live near shore. The best-known species is the harbor porpoise, found across the northern hemisphere.

Porsche (1931–): German high-performance automaker.

portability (software): the ease with which source code or a computer program may be transferred to a different computer operating system.

portal vein (aka hepatic portal vein): a blood vessel that conducts oxygen-poor but nutrient-rich blood from the gastrointestinal tract and spleen to the liver.

Portuguese man o’ war (aka Man-of-war, bluebottle, floating terror, Physalia physalis): a marine siphonophore, with venomous tentacles that deliver a nasty sting. This creature is a colony of specialized individuals (zooids), so physiologically integrated that they are incapable of independent survival.

positivism: the idea that valid knowledge (truth) is only had via logical treatment of sensory experience. Positivism rejects introspection and intuition as sources of knowledge. Contrast antipositivism.

positron: the antimatter equivalent of the electron.

positron emission tomography: a medical imaging technology that detects gamma rays emitted from a positron-emitting radioactive tracer in the body.

post-translational processing: modification of a protein after its translation, including attaching other biosynthetic functional groups or making structural changes.

posterior chamber: the small space directly behind the peripheral part of the iris but anterior to the lens.

positivism: the idea that valid knowledge (truth) is only had via logical treatment of sensory experience. Positivism rejects introspection and intuition as sources of knowledge. Contrast antipositivism.

post-traumatic stress disorder (PTSD): a terrifying event in the past echoing onto present awareness.

potash: potassium carbonate (K2CO3), a water-soluble potassium salt.

potassium (K): the element with atomic number 19; an alkali metal with a single valence electron that readily reacts. Potassium is essential to all cells.

potato: a tuber of the perennial nightshade Solanum tuberosum. The potato plant is native to the Andes mountains. It was domesticated by Peruvians 10,000 years ago and is now eaten worldwide.

potato blight (Phytophthora infestans): an oomycete that blights potatoes.

potato bug (aka Colorado potato beetle, Leptinotarsa decemlineata): a 1-cm beetle with a bright yellow/orange body, and 5 bold, brown stripes that run the length of its elytra.

potential (electric): see electric potential.

potential energy: stored energy that may be released; the energy inherent in an object owing to its position relative to other objects, internal stresses, electric charge, and other factors.

potoroo: a rat-like Australian marsupial. The 3 still-extant species of potoroo will soon be extinct, thanks to habitat loss, introduced species (especially foxes), and their being considered a pest to crops.

potto: a quiet, slow-moving central African strepsirrhine that inhabits the canopy of rain forests.

poultry (agriculture): a domesticated bird kept for eggs or meat.

poultry (food): bird meat.

pouteria: a flowering tree in the Pouteria genus, widespread throughout the tropics. Pouteria maxima is a keystone species in the rainforests of Guyana.

poxvirus: a virus in the Poxviridae family which infects arthropods and vertebrates, including humans. The best-known poxvirus is smallpox.

power (mathematics) (aka exponent): how many times to use a number in a multiplication.

power (physics): the amount of energy transferred via current per unit of time, measured in watts (power = watts / time). Power is a measure of how quickly work is done.

power distance: Geert Hofstede’s term for societal range of social stratification.

power law: a consistent mathematical relationship between 2 quantities, such as the magnitude of an event as a function of its frequency (e.g. earthquakes or solar flares).

pragmatism (philosophy): a philosophy that rejects the idea that thought serves to comprehend reality; instead, cognition is a tool for problem-solving and decision-making. Pragmatism began in the United States around 1870.

prāņā: the Sanskrit word for “life force.”

prāņāyāma: a breathing technique.

prairie vole (Microtus ochrogaster): a small vole native to central North America.

prayer plant (Maranta leuconeura): a perennial, native to Brazilian tropical forests, so called for its habit of laying its leaves out flat during the day and folding them erect at night.

pre-adaptation: a by-product of adaptation that is later adaptively employed. Pre-adaptations are a fundamental mechanism of evolvability.

precarity: existence without economic security or predictability.

precession: a slow gyration in rotation axis of orbital body.

precipitate (verb): to separate from solution or suspension.

precipitation: rain, sleet, ice, snow, and fog; also defined as the quality of being precipitate, or hasty.

precipitation (chemistry): formation of a solid within a solution. The solid formed is termed a precipitate. The chemical agent that provokes solidity is the precipitant.

precocene: a compound produced by plants that inhibits juvenile hormone biosynthesis in insects.

precocial: animal species with relatively mature and mobile young from the moment of birth or hatching. Many, though not all, arthropods, fish, amphibians, and reptiles are precocial. Contrast altricial.

precocious knowledge: inborn knowledge. Precocious knowledge is a telltale of energyism, as it cannot be explained via materiality.

preconscious: a Freudian construct of thoughts which are conceived at the unconscious, but not subject to repression, and so are capable of becoming conscious. Compare unconscious, conscious. See subconscious.

predator: an organism that consumes other animals as a primary food source. A top predator is a predator that is not preyed upon by another organism (pathogens aside). Compare herbivore, omnivore, and saprovore.

predator satiation: an animal species population being so concentrated in an area that some survive despite predation.

predeterminism (aka fatalism): the idea that events are determined in advance.

predictable (adjective): foreknowable; capable of being known in advance or anticipated.

predictable-world bias: a tendency to see order where it does not exist.

preformation: the process of producing primordial germ cells via germ plasm.

preformationism: the disproven hypothesis that organisms develop from miniature versions of themselves – developmental biology as a process of supersizing. Contrast epigenesis.

prefrontal cortex: the front portion of the frontal cortex lobe; associated in humans with the executive system.

prehensile: adapted for grasping by wrapping around. Paws, hands, feet, and tails may be prehensile.

prehistory: hominin history prior to written records. The term was introduced by Daniel Wilson in 1851, used by Darwin in his 1959 Origin book, and given wider application by John Lubbock in 1865.

prejudice: a preconceived negative attitude toward members of a social group. Compare discrimination.

premise: a proposition supportive of a conclusion.

presence (spirituality): a felt external (ED) spirit.

present bias: the preference for rewards in the near future as contrasted to later.

presocial: an animal species that lacks 1 of the 3 following characteristics: 1) reproductive division of labor; 2) cooperative care of the young; and 3) overlapping generations. Contrast eusocial.

prevaricate: to lie or speak misleadingly.

Prevotella: a genus of bacteria, found in abundance in the gut flora of humans who eat a healthy diet, high in carbohydrates. See Bacteroides, Ruminococcus.

price mechanism: the manner in which prices affect the demand and supply of goods and services.

prickly pear cactus: a cactus in the genus Opuntia, native to the Americas.

prima facie: on first appearance.

primary group: a group of people with high affinity, such as family or friends. Compare secondary group.

primary growth: plant cell division at the tips of roots and stems, causing elongation. Compare secondary growth.

primary metabolite: a compound produced by a plant that is essential to its survival. Compare secondary metabolite.

primate: a mammal order containing prosimians (neither monkey nor ape) and simians (monkeys and apes).

primatology: the study of primates.

prime number: a natural number greater than 1 that cannot be formed by multiplying 2 smaller natural numbers.

primeval forest (aka virgin forest, old-growth forest): a forest having obtained great age without major ecological disturbance. Contrast secondary forest.

primitive (evolutionary biology): evolved early compared to later organisms in a clade.

primogeniture: the system of succession by the firstborn son.

priming: an implicit memory recall effect via stimulus that is somehow related to the implicit memory.

primordial germ cell: a germ cell that produces a gamete.

principle (philosophy of science): a conceptual construct explaining some countenance of Nature.

principal (finance): the nominal amount of a debt. See interest.

principle of least action (aka principle of stationary action): a variational principle which can be used to get the equations of motion for a physical system. The principle of least action can derive Newtonian, Lagrangian, Hamiltonian, and general relativity (Einstein–Hilbert) motion equations.

principle of least time: see Fermat’s principle.

Principia (Mathematical Principles of Natural Philosophy) (1687): Isaac Newton’s 3-volume work laying the foundation of classical physics; considered one of the most important works in the history of science.

prinia: a small insectivorous passerine in the Prinia genus.

printed circuit board (PCB): a nonconductive planar sheet (typically glass epoxy) with conductive (commonly copper) electronic circuitry pathways embedded on its surface. PCBs also have holes into which ICs and other computer components are soldered on.

prion: an infectious agent in the form of a misfolded protein.

prisoner’s dilemma: a game theory situation where 2 individuals acting in their own self-interest do not produce an optimal outcome compared to cooperation; originally conceived by Merrill Flood and Melvin Dresher in 1950.

private good: a good that is excludable and rivalrous. Anything that diminished by consumption is a private good (rivalrous). Anything that is private property is a private good (excludable). Contrast public good.

probability: the likelihood of an event.

probability curve: a curve that describes the distribution of probability of an event based upon statistical sampling.

probability value (p-value): a statistical indication that a proposed hypothesis may be plausible.

problem: a dynamic not understood for which a solution is sought (problem-solving). Whereas problem-solving which shapes matter is craftwork, entirely abstract (non-material) problem-solving is symwork (of symbolic representations).

proboscis: an elongated appendage from the head of an animal. In invertebrates, the proboscis usually refers to the tubular mouth parts used for feeding. In vertebrates, the term is descriptive of a snout (e.g., shrews, tapirs, elephants).

proboscis monkey (aka long-nosed monkey): a reddish-brown arboreal monkey with an outsized nose, endemic to the mangrove swamps of Borneo.

procambium: the primary meristem that develops into a plant’s vascular system. The procambium is inside the protoderm.

procedural memory (aka implicit memory): memory of a learned skill. Contrast declarative memory.

processor (computer): a hardware unit, typically a single IC chip, that processes software.

Prochlorococcus: a genus of tiny marine cyanobacteria.

Proconsul (23–5 mya): an early hominid.

producer (biology) (aka autotroph): an organism capable of sustaining itself by inorganic means. Plants are producers. Contrast consumer.

program (software): a computer-executable set of instructions. Compare application.

programmed cell death: cell death mediated by an intracellular program.

progressive provisioning: partially digesting food and passing it to another organism, typically offspring.

projection (psychology): an attribution of personality trait with insufficient evidential behavioral basis; as a Freudian defense mechanism, a person unconsciously ascribes to another one’s own unacceptable attributes.

prokaryote: an organism that lacks a cell nucleus or other membrane-bound organelles. While prokaryotes are strictly single-celled, most can form stable, aggregate communities, such as a biofilm. Compare eukaryote.

prolactin (aka lactotrope): a hormonal protein with various functions among different species.

promote (chemistry): encourage chemical reaction.

promoter (genetics): a region of DNA that facilitates the transcription of a certain gene.

proof (mathematics): an inferential argument as a statement, based upon axioms and postulates. Compare theorem.

propaganda: information or argument intended to help or harm an individual, group, movement, institution, or nation.

propagule: a structure, such as a seed, spore, or cutting, that propagates a plant or other organism.

propane (C3H8): a 3-carbon alkane gas at ambient temperature and pressure, but compressible to a transportable liquid. Commonly used as a fuel, propane is a by-product of natural gas processing and petroleum refining.

property (economics): objects which may be owned. Ownership of land is called real property.

prophet: a guru that teaches reality and the consequences of ignorance.

prophage: a bacteriophage genome inserted and integrated into a bacterium’s genome.

prophase: the 1st stage of mitosis, in which chromatin condenses. See metaphase, anaphase, telophase, interphase.

propolis: a resinous mixture that honeybees produce from resin collected from sap flows, tree buds and other sources. Propolis is used to seal cracks, and so weatherproof a hive. Propolis is also used medicinally, to get help cure bacterial or fungal infections.

proprioception: an organism’s sense of physical self, including the relative position of various body parts and their employment, and as well the energy required for movement or other activity.

prosimian: the suborder of primate which includes lemurs, bushbabies, and tarsiers, among others. See simian.

prosody: the rhythm, stress, and intonation of speech.

prospect theory (economics): a descriptive behavioral economic theory which posits that people make decisions based on the potential of immediate loss or gain rather than a probabilistic final outcome.

prospect theory (psychology) (aka loss-aversion theory): a theory of psychology concerning how people choose among alternatives which involve risk. Prospect theory assumes people are more averse to loss than desirous of gain. Prospect theory incorporates framing effect. Prospect theory was proposed by Daniel Kahneman and Amos Tversky in 1979, and further developed in 1992.

prospective memory: a memory relating to the future. Contrast retrospective memory.

Prosperpinus: a genus of sphinx moth with 7 species, including the yellow-banded day sphinx (P. flavofasciata), the Terloo sphinx (P. terlooi), and the Pacific green sphinx (P. lucidus).

protandry: a male that can change into a female.

protease (aka peptidase, proteinase): an enzyme that abets proteolysis. { Spokes 1 }

protease (aka peptidase, proteinase): an enzyme employed by all organisms to facilitate digestion, particularly breaking apart the peptide bonds that hold amino acids together.

proteasome: a protein complex within all eukaryotes and archaea, and in some bacteria. In eukaryotes, proteasomes are in the nucleus and the cytoplasm. The primary work of a proteasome is breaking down unneeded or damaged proteins via proteolysis. Enzymes that carry out proteolysis are proteases. Proteasomes are part of a major mechanism by which cells regulate the concentration of proteins and recycle portions of misfolded proteins.

protein (molecular biology): a single, long, linear polymer chain of amino acids that typically takes a folded structure; a complex organic macromolecule by which living bodies are intelligently built. See enzyme.

protein: a complex organic macromolecule by which living bodies are intelligently built. See enzyme. { Clarity }

protein (nutrition): protein-laden food which is broken into amino acids during digestion for bodily absorption.

protein synthesis: the multiple-stage process of protein production based upon a genetic template.

Proteobacteria: a phylum of bacteria. Some are pathogens. Others are nonparasitic. Many nitrogen-fixing bacteria are Proteobacteria.

proteolysis: protein catabolism by hydrolysis of peptide bonds.

proteome: (the idea of) the entire set of proteins expressed by a cell’s or organism’s genome.

Proterozoic (2.5 bya–542 mya): the 3rd of 4 geological eons, characterized by early life (based upon an outdated estimate, lasting up to the Cambrian period).

Protestant Reformation (1517–1648): a doctrinal schism from the Catholic Church initiated by Martin Luther.

Protestantism: the branch of Christianity that developed from the Protestant Reformation.

prothallus: the gametophyte stage in the life of a fern or other pteridophyte (a vascular plant that does not produce seeds).

protist: a catchall kingdom of eukaryotic organisms, including algae and amoeba. Most protists are unicellular, though many practice pluricellularity.

protium (botany): a medicinal plant of over 140 species, with antioxidant and detoxifying compounds.

protium (chemistry): the most abundant form of hydrogen, comprising a nucleus of a single proton (no neutron). Contrast deuterium.

protocell: a cellularly-contained set of chemical reactions with evolutionary potential.

protoderm: the primary meristem that develops into a plant’s epidermis (outer layer of tissue).

protogyny: a female that can change into a male.

proton: a positively charged hadron that is a constituent of every atomic nucleus. The simplest hydrogen atom comprises a proton nucleus with a single electron orbiting about it. See neutron.

proton–proton chain reaction: a fusion reaction by which stars convert hydrogen to helium. The proton–proton chain reaction dominates fusion in stars the size of the Sun or smaller. See carbon–nitrogen–oxygen (CNO) cycle.

proton flux: the passage of protons through a cell membrane.

proton pump: a protein, integral to a cellular membrane, that can push protons across a cell or organelle membrane. Proton pumps create a proton gradient, causing a differential in pH and electrical charge, thus creating an electrochemical potential which works as an energy storage unit (like a battery). Energy from ATP comes via a proton pump.

proton transfer: movement of a proton from one atom to another.

protostome: a clade of animals comprising annelids (segmented worms), arthropods, and mollusks. The sister clade of protostomes are deuterostomes, from which evolved echinoderms (e.g., sea urchins) and vertebrates.

protozoan (plural: protozoa): a single-celled, typically microscopic heterotroph. Protozoa live in aqueous environments and soil. They occupy a range of trophic levels. Protozoa are called animal-like protists because they subsist on other organisms.

Protungulatum: an extinct genus of mammals that lived during the Cretaceous and early Paleocene; the progenitor of all placental mammals.

proxemics: the (study of the) use of space in social interaction, especially as a facet of nonverbal communication.

Proxima Centauri (aka Alpha Centauri C): a small, low-mass, red dwarf star 4.244 light-years from the Sun, in the constellation Centaurus.

prymnesin (C93H137Cl2NO36): a phycotoxin produced by Prymnesium parvum.

Prymnesium parvum: a species of golden algae that can both photosynthesize and carnivorously hunt via cooperatively- produced venom (prymnesin).

pseudocoelomate: an animal with a body cavity with loosely organized organs, as contrasted to coelomates, with quite organized organs (such as all vertebrates), or acoelomates, like flatworms, who have no body cavity at all.

Pseudomonas: a diverse genus of plant-related bacteria with 191 species. Some are plant symbionts, others pathogenic.

Pseudomonas aeruginosa: a common rod-shaped bacterium resident in soil and water. P. aeruginosa can cause disease in plants and animals, including humans. P. aeruginosa is antibiotic resistant.

Pseudomonas carboxydovorans (aka Oligotropha carboxidovorans): a soil bacterium that consumes carbon monoxide.

Pseudomonas putida: a beneficial rhizobacterium.

Pseudomonas syringae: a pathogenic bacterium that can infect a wide variety of plants, causing characteristic brown spots. P. syringae is a common cause of surface frost damage in plants. P. syringae produces coronatine, which confuses a plant’s defense system.

Pseudomyrmex: a genus of wasp-like, stinging (venomous) ants. Certain species, including P. triplarinus and the P. viduus group, have a mutually protective mutualism with Triplaris trees: the ants fiercely protect the tree from all comers in return for lodgings within the tree and a wholesome diet.

pseudopod (aka pseudopodium; plural: pseudopods or pseudopodia): a temporary cytoplasm-filled projection from a unicellular protist or eukaryotic cell used for motility; from the Greek for “false foot.”

pseudoscorpion: an arachnid resembling a scorpion in having front pincers and a flat, pear-shaped body, but lacking the scorpion’s tail stinger. Some pseudoscorpions have elaborate mating dances.

psilocin (C12H16N2O): the psychoactive ingredient in psilocybin mushrooms.

psilocybin (C12H17N2O4P): an alkaloid produced by over 200 mushroom species to deter fungivores. Psilocybin metabolizes to psilocin. Ingested by humans, psilocybin is an agent of dissociation. In high doses, psilocybin is hallucinogenic.

psyche: the psychological structure of an organism, especially as a motive force.

psychedelic: a substance which can induce hallucinations.

psychiatry: the study of mental disorders, their diagnosis, and treatment.

psychic energy (aka mental energy): the inherent energy in a psyche. Aristotle conceived of actus et potentia: dynamic potential. Henry More identified an “energy of the soul” in 1642. In 1874 Ernst Wilhelm von Brücke described the life-energy system (lengyre) as “psychodynamics.” von Brücke supervised 1st-year medical student Sigmund Freud, who adopted the idea. In 1928 Carl Jung published an essay on psychic energy. Psychic energy and psychodynamics were promoted by Alfred Adler, Melanie Klein, and Katharine Cook Briggs, among others.

psychoactive (aka psychotropic): a substance that affects sensation or cognition.

psychoanalysis: a method of psychological therapy originated by Sigmund Freud in the mid-1890s in which a patient freely talks (free association) about their mental turmoil as a means for insight. The key assumptions behind psychoanalysis are that the mind represses relevant information for a healthy mental life, and, most saliently, that the fabrications of the mind are not in of themselves the problem.

psychobiology (aka biological psychology, biopsychology, behavioral neuroscience): the school of thought which treats psychology as an adjunct to biology.

psychological complex: a debilitating emotional complex.

psychological distance: the mentally construed remove from an object, person, or event.

psychological field theory: a hypothesis by Kurt Lewin that a person’s “psychological field” dynamically emerges from the individual’s “life space.”

psychology: the study of the mind, leading to philosophy about the mind. There can be no science of the mind. An individual psychology is characterized by mental and behavioral habits.

psychometrics: the study and technique of taking psychological measurements.

psychopath: a person without an innate sense of empathy.

psychopathy: a mental disorder characterized by impaired empathy, lack of remorse, and bold, disinhibited egotism. Lack of empathic feelings hinders social learning. Psychopathy has had different conceptions throughout history and remains controversial. See sociopathy.

psychophysics: the study of the relation between stimuli and the senses with regard to physics and psychology.

psychophysical isomorphism: the hypothesis that perceptual phenomena correspond with brain activity, not necessarily sensory stimuli; a fundamental principle of Gestalt psychology. Compare constancy hypothesis.

psychophysiology: the study of perception – how physical events are experienced psychologically.

psychopomp: one who guides souls; specifically refers to the ancient Greek belief in conducting souls to the afterworld.

psychosis: the substitution of experienced actuality with a paracosm. Compare neurosis.

psychosoma: a bodily condition psychologically provoked.

psychospace: the mental, as contrasted to physical, spatial and temporal environment. See psychological distance.

psychotherapy: a general term for psychological treatment via conversation, sometimes along with other techniques.

psychotropic: see psychoactive.

psychrophile: an extremophilic organism adapted to cold (–15 to 9 °C).

ptarmigan (aka Rock Ptarmigan): a sedentary, herbivorous, medium-sized bird in the grouse family.

pteridophyte: a vascular plant that reproduces and disperses via spores, producing neither flowers nor seeds.

Pterodactylus: a carnivorous flying pterosaur genus, likely piscivorous.

pterosaur (228–66 mya): the first flying vertebrates, neither dinosaur nor the ancestor of birds.

ptyalin: an enzyme that breaks down starches.

public good: something that is publicly shared. By contrast, a private good is possessed or consumed by an organism with limited or no sharing.

public good: a good that is non-excludable and non-rivalrous. Consumption of a public good by one individual does not diminish its consumption by others. Contrast private good. { Spokes 6 }

publican: a tavern (public house) keeper. In antiquity, notably the Roman Empire, publicans were public contractors.

puffball: a round fungus which contains and emits brown, dust-like spores.

puffbird: a small, carnivorous, tropical, near passerine native to Mexico and South America.

pufferfish: a mostly tropical estuarine fish that produces a defensive neurotoxin.

pulsar (portmanteau of pulsating star): a magnetized, rotating neutron star that emits electromagnetic radiation.

pulse (food): a legume harvested for its dry seed. Dried beans, peas, lentils, and peanuts are pulses.

pulvinus: a joint-like thickening of plant cells at the base of a leaf that facilitates growth-independent movement.

puma (aka cougar, mountain lion, Puma concolor): a large, secretive felid.

pumice: a solidified, frothy, lava rock.

punctuated equilibria hypothesis: the hypothesis that speciation occurs in spurts, with long durations of evolutionary stability. Compare turnover pulse.

pupa (plural: pupae or pupas): a development stage in an insect: typically quiescent, often enclosed in a cocoon or case, after the larval stage of development, before emerging as an adult.

pupil (physiology): the variably sized hole in the center of the iris that allows passage of light to the retina.

purgative: something that works as a cathartic or laxative.

purine: a chemical class of organic compounds, notably including nucleobases adenine (A) and guanine (G).

purple bacteria: a phototrophic bacteria group that includes Escherichia.

purple loosestrife (Lythrum salicaria): a herbaceous perennial native to northwest Africa, Europe, Asia and southeastern Australia.

purple pitcher plant (northern pitcher plant, turtle socks, side-saddle flower, Sarracenia purpurea): a carnivorous plant endemic to the bogs and infertile sandy soils of North America.

purposive behavior: action(s) taken expecting a specific outcome.

pus: a yellowish exudate (exuded substance) that forms at the site of inflammation during infection. Neutrophils are the primary constituent of pus.

Puschkinia: a genus of bulbous perennials with 2 species, native to the Middle East and Asia.

Pusey-Barrett-Rudolph theorem: that wave/particle duality is

pusillanimity: timidity, cowardliness.

pygmy pipe (aka sweet pinesap, Monotropsis odorata): a flowering plant that employs camouflage to protect its flowers, disguising them as woodland leaf litter.

pyogenic: generating pus.

pyramidal saxifrage (Saxifraga cotyledon): a long-lived European alpine plant with thick, dense leaves, adapted to stressful environments.

Pyrenean rocket (aka Austrian rocket, Sisymbrium austriacum): a small flowering plant native to the mountains of southern Europe.

pyrethrum : an insecticide derived from chrysanthemum flowers.

pyrimidine: a chemical class of organic compounds, notably including nucleobases cytosine (C), thymine (T) and uracil (U).

pyrite (FeS2): iron sulfide; nicknamed “fool’s gold.”

pyridoxal (C8H9NO3): 1 of 3 natural forms of vitamin B6.

pyroelectricity: a property of certain crystals to be naturally electrically polarized and thereby have large electric fields.

pyroptosis: an inflammatory form of programmed cell death.

pyrrolizidine alkaloid (PA) (aka necine base): a plant-produced alkaloid based upon pyrrolizidine (C7H13N), toxic to many insect herbivores.

pyruvate (C3H4O3): a metabolic product of glucose from glycolysis. Pyruvic acid supplies energy to cells when oxygen is present (aerobic respiration), and alternatively ferments to produce lactate during anaerobic exertion, when oxygen is lacking.

Pythagorean theorem: though previously known by the Babylonians and Indians, a geometry theorem credited to Pythagoras: for any right-angled triangle with ‘c’ as the hypotenuse, c2 = a2 + b2.

python (family): a nonvenomous snake in the Pythonidae family, with 31 species in 8 genera, endemic to Africa, Asia, and Australia.

python (genus): a nonvenomous snake of 11 extant species in the Python genus, endemic to Africa and Asia.