Piñon, small, low-growing nut pines (genus Pinus) of the southwestern United States and northern Mexico.
21st Century Webster's Family Encyclopedia - Pimento to Popcorn
Pimento, tree (Pimenta officinalis) of the myrtle family whose small berry-like fruit is used to make the spice allspice.
Pimpernel (Pimpinella magna), perennial plant that grows along the edges of woods and in many meadows; the rootstock is used for medicinal purposes, in treating sore throats, colds, bronchitis, and inflammation of the larynx.
Pinching bug See: Stag beetle.
Pinchot, Gifford (1865–1946), U.S. politician and conservationist who was largely responsible for making conservation a public issue.
Pinckney, South Carolina family whose members were notable in the founding period of the republic.
Pinckney Treaty (1795), negotiated with Spain by Thomas Pinckney, establishing commercial relations with Spain, opening the entire Mississippi River to U.S. navigation, granting Americans the right of deposit at New Orleans, and fixing the boundaries of Louisiana and east and west Florida.
Pindar (518–438 B.C.), ancient Greek lyric poet, inventor of the Pindaric ode, a poetic form in which complex rhythms in a series of stanzas hailed the victors in national athletic contests such as the Olympics.
Pine, common name for the evergreen conifer trees of the family Pinaceae.
Pine siskin, North American bird (Spinus pinus) of the finch family, measuring about 5 in (13 cm) in length.
Pineal gland, pea-sized glandlike structure situated over the brain stem that appears to be a vestigial remnant of a functioning endocrine gland in other animals.
Pineapple, short-stemmed plant (Ananas comosus) with pointed, spiny leaves.
Pinero, Sir Arthur Wing (1855–1934), British playwright known both for his farces and for his plays based on social realism.
Pink, common name for various flowering plants in the family Caryophyllaceae.
Pink bollworm, small, dark-brown moth (Pectinophora gossypiella) of the gelechiid moth family.
Pink-eye See: Conjunctivitis.
Pinkerton, Allan (1819–84), Scottish-born U.S. founder of a pioneer detective agency.
Pinochet Ugarte, Augusto (1915– ), president of Chile (1973–88).
Pinochle, card game played with a 48-card deck containing 2 each of the cards 9, 10, jack, queen, king, and ace in each of the 4 suits.
Pinta See: Columbus, Christopher.
Pintail, duck (Anas acuta) of the family Anatidae.
Pinter, Harold (1930– ), English dramatist and stage director.
Pinworm, parasitic nematode worm (family Oxyuridae) that infests the intestines of vertebrates.
Pinzón, family of 3 Spanish brothers, navigators who took part with Columbus in discovering America.
Pion See: Meson.
Pioneer life in America, way of life characteristic of the people who first settled the western reaches of the continental United States. Pioneer life in America has two aspects. It is the story of migration and settlement. It is also an important part of American identity, one of the fundamental images Americans have of themselves, and an important part of the development of the country's …
Pipal See: Bo tree.
Pipe, musical instrument consisting of a tube of wood or metal, that produces sounds when air is blown through it.
Pipe, long hollow tube that transports gas, steam, or liquids.
Pipe, hollow stem connected to a small bowl used for smoking tobacco.
Pipefish, eellike fish with tubular mouth of the family Syngnathidae.
Pipeline, tube for conveying fluids—liquids, gases, or slurries.
Pipit, small songbird (family Motacillidae) of open country that looks and sings rather like a lark.
Piraeus (pop. 196,400), city in Greece.
Pirandello, Luigi (1867–1936), Italian dramatist and author, winner of the 1934 Nobel Prize for literature.
Piranesi, Giovanni Battista (1720–78), Italian etcher, draftsperson, and architect, known for his prints of old and contemporary Roman buildings, Views of Rome (begun 1748), and for a series of fantastic Imaginary Prisons (c.1745).
Piranha, or caribe, small, extremely ferocious, shoaling freshwater fish (family Characidae) of South America.
Pirate, person who robs ships at sea.
Pisa (pop. 97,900), historic city in the northwestern region of central Italy, on the Arno River in Tuscany.
Pisa, Council of (1409), uncanonical Roman Catholic Ecumenical Council of 500 prelates and delegates from throughout Europe that met to try to heal the Great Schism.
Pisa, Leaning Tower of See: Leaning Tower of Pisa.
Pisano, Nicola (1210?–1278), Italian sculptor.
Pisistratus, or Peisistratus (600–527 B.C.), tyrant of Athens, whose benign rule and fostering of commerce and the arts made Athens the foremost city in Greece.
Pissarro, Camille (1830–1903), French impressionist painter.
Pistachio nut (Pistacia vera), seed of the pistachio tree in the cashew family.
Piston, Walter (1894–1976), U.S. neoclassical composer, professor of music at Harvard (1926–60).
Pit bull, any of several breeds or crossbreeds of dogs having a mixture of bulldog and terrier.
Pit viper, predominantly New World venomous snake (family Crotalidae).
Pitcairn Island, British colony (2 sq mi/4 sq km) in the Pacific Ocean midway between New Zealand and Panama, famous as the uninhabited island settled by Bounty mutineers and Tahitian women (1790).
Pitch, frequency of the vibrations constituting a sound.
Pitchblende, or uraninite, brown, black, or greenish radioactive mineral, the most important source of uranium, radium, and polonium.
Pitcher, Molly (Mary Ludwig McCauley; 1754–1832), heroine of the American Revolution.
Pitcher plant, name given to several insect-eating plants of 3 different families (North American, Old World, and Australian) in which the leaves form a pot-shaped trap for insects.
Pitt, name of 2 English statesmen. William, 1st Earl of Chatham (1708–78), known as Pitt the Elder and a noted orator, was war minister during the Seven Years' War (1756–63). Through defeating the French, by 1761 he had gained imperial supremacy for Britain in Europe, Canada, and India, and made the British navy a formidable force. Out of office after 1768, he opposed taxing A…
Pitti Palace, palace in Florence, Italy.
Pittsburgh (pop. 366,800), steel-producing city in southwestern Pennsylvania, seat of Allegheny County, and the state's 2nd-largest city.
Pituitary gland, major endocrine gland, situated just below the brain, under the control of the adjacent hypothalamus and in its turn controlling other endocrine glands.
Pius, name of 12 popes. Saint Pius V (Michele Ghislieri; 1504–72), an Italian, was elected in 1566. With some severity he restored a degree of discipline and morality to the papacy in the face of the Protestant challenge and organized the Spanish-Venetian expedition that defeated the Turks at Lepanto in 1571. Pius VII (Gregorio Luigi Barnaba Chiaramonti; 1740–1823), an Italian, was e…
Pizarro, Francisco (c. 1474–1541), Spanish conquistador who destroyed the Inca empire in the course of his conquest of Peru.
PKU See: Phenylketonuria.
Placebo, tablet, syrup, or other form of seeming medication that is inactive, prescribed in lieu of active preparations.
Placenta, specialized structure derived from the uterus lining and part of the embryo after implantation.
Placentia (pop. 2,000), town in southeastern Newfoundland, Canada.
Plagiarism, the act of copying another's work (ideas, writings, or other creative work) and presenting it as one's own.
Plain, expanse of nearly level land, usually surrounded by higher land forms.
Planarian, type of flatworm (turbellarian) having a flat, long body and broad head.
Planck, Max Karl Ernst Ludwig (1858–1947), German physicist whose quantum theory, with Albert Einstein's theory of relativity, ushered physics into the modern era.
Plane, in mathematics, surface having only length and breadth, any 2 points of which can be joined by a straight line composed entirely of points also in the plane.
Plane tree See: Sycamore.
Planet, in the solar system, 1 of the 9 major celestial bodies (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto) orbiting the sun; by extension, a similar body circling any other star.
Planetarium, optical device representing the relative positions and motions of celestial objects on the interior of a hemispherical dome.
Planetoid See: Asteroid.
Plankton, microscopic marine animals and plants.
Planned Parenthood Federation of America, organization that promotes voluntary family planning in the United States and developing countries.
Plant, living organism belonging to the plant kingdom (Planta). Green plants are unique in being able to synthesize their own organic molecules from carbon dioxide and water, using light-energy, by the process known as photosynthesis. Mineral nutrients are absorbed from the environment. Plants are the primary source of food for all other living organisms. The possession of chlorophyll, the green p…
Plant louse See: Aphid.
Plantagenet, name given to the branch of the Angevin dynasty descended from Geoffrey Plantagenet that ruled England from 1154 to 1485.
Plantain, group of herbs in the family Plantaginaceae.
Plantain lily See: Day lily.
Plantation, large farm on which a crop is planted, tended, and harvested by workers who live there.
Planting See: Agriculture.
Plasma, in physics, almost completely ionized gas containing equal numbers of free electrons and positive ions.
Plasma, in biology, fluid portion of the blood, including fibrinogen; distinguished from serum, from which fibrinogen has been separated.
Plaster, mixture of water, sand, and lime used to coat walls and ceilings.
Plastic, material that can be molded (at least in production) into desired shapes. A few natural plastics are known, e.g., bitumen, resins, and rubber, but almost all are synthetic, made mainly from petrochemicals. They have a vast range of useful properties, including hardness, elasticity, transparency, toughness, low density, insulating ability, inertness, and corrosion resistance. Plastics are …
Plastic explosive, putty like, flexible explosive.
Plastic surgery, branch of surgery devoted to reconstruction or repair of deformity, surgical defect, or the results of injury.
Plate tectonics See: Tectonics; Volcano.
Plateau, high plain.
Platform tennis, game resembling tennis in which players use paddles to hit a sponge rubber ball back and forth over a net.
Plath, Sylvia (1932–63), U.S. poet whose taut, melodic, highly imagistic works explore the nature of womanhood and her fixation with death.
Platinum, chemical element, symbol Pt; for physical constants see Periodic Table.
Plato, Greek philosopher (c.427–347 B.C.).
Platt Amendment, provision forced through Congress and into the Cuban constitution by Senator Orville Platt in 1901.
Platte River, river in Nebraska, U.S.
Plattsburgh (pop. 21,057), largest city in northeastern N.Y.
Platyhelminth See: Flatworm.
Platypus, or duck-billed platypus (Ornithorhynchus anatinus), amphibious monotreme (egg-laying mammal) found in Australia and Tasmania.
Plautus (c.254–184 B.C.), Roman writer of comedies, 21 of which have survived.
Play, in animals, a distinctive type of behavior of both adults and juveniles, of unknown function and involving the incomplete, ritualized expression of normal adult behavior patterns.
Plea bargaining, agreement between the accused and the prosecutor under which the accused agrees to plead guilty to a lesser offense in order to receive a lighter sentence from the judge.
Plebeians, nonaristocratic classes in ancient Rome.
Plebiscite, in Roman history, law enacted by the plebeian comitia, or assembly of tribes.
Plecoptera, or stonefly, order of insects that lays eggs in water.
Pledge of Allegiance, promise of loyalty to the United States.
Pleistocene Epoch, also known as the Great Ice Age, an earlier epoch of the Quaternary Period, stretching from between c.2 million and 3 million through 10,000 years ago.
Plekhanov, Georgi Valentinovich (1857–1918), Russian Marxist thinker.
Plesiosaur, huge, prehistoric marine reptile now extinct.
Pleura, thin connective membrane that covers the inside of the thorax (chest cavity) and the lungs in mammals.
Pleurisy, inflammation of the pleura, the thin membrane covering the outer lung surface and the inner chest wall.
Plexiglas, trademarked name of a type of plastic.
Plexus, network of stringlike structures, such as of nerves or blood vessels.
Plimsoll mark, line or series of lines on the side of a seagoing ship indicating the safe loading limit.
Pliny, name of 2 Roman authors.
Pliocene, final period of the Tertiary, immediately preceding the Quaternary, c. 5–1.8 million years ago.
PLO See: Palestine Liberation Organization.
Ploiesti (pop. 252,100), large city in southeastern Romania, center of the Romanian oil industry.
Plotinus (205?–270?), Greek philosopher, founder of Neoplatonism.
Plovdiv (pop. 379,100), second-largest city in Bulgaria, situated on the Maritsa River.
Plover, common name for various small or medium-sized wading birds of the family Charadriidae, which includes the lapwings and the true plovers.
Plow, implement for tilling the soil: breaking up the surface crust for sowing and turning under stubble and manure.
Plum, common name for many species of trees (genus Prunus) of the rose family that produce soft-fleshed fruits enclosing a single pit.
Plumbago, any of several plants and shrubs belonging to the leadwort family, grown mostly in warm climates.
Plumbing, system of pipes and fixtures through which water and drainage flow into and out of a building.
Plutarch (c.A.D. 46–c.A.D. 120), Greek philosopher and biographer.
Pluto, in astronomy, ninth planet of the solar system, orbiting the sun at a mean distance of 3.67 billion mi (5.9 billion km) once every 248.4 years.
Pluto, in Greek and Roman mythology, ruler of the underworld and god of the dead.
Plutonium, chemical element, symbol Pu; for physical constants see Periodic Table.
Plymouth (pop. 35,913), town in southeastern Massachusetts, the site where the Pilgrims came ashore from the Mayflower on Dec. 21, 1620, and where they established the second permanent English settlement in America.
Plymouth (pop. 257,500), city in Devon county, southwest England, on Plymouth sound, from which the Mayflower sailed in 1620.
Plymouth Colony, first English settlement in what is now New England, second permanent English settlement in America, founded by the Pilgrims in 1620.
Plymouth Company, speculative joint-stock company founded in 1606 by a group of English “merchant adventurers.” Its purpose was to colonize the coast of North America and thus increase English wealth and trade.
Plymouth Rock, granite boulder off the shore at Plymouth, Mass., on which, according to tradition, the Pilgrims first set foot in America in 1620.
Plywood, strong, light wood composite made of alternate layers of veneer glued together with their grain at right angles.
Plzen (pop. 173,000), city in Bohemia, a western region of Czech Republic.
Pneumoconiosis See: Black lung.
Pneumonia, inflammation and consolidation of lung tissue (giving it a solid consistency).
Pneumothorax, condition in which air is present in the pleural space between the lungs and the chest wall.
Pnom Penh See: Phnom Penh.
Pocahontas (1595–1617), Native American who strove to improve relations between Native Americans and English settlers in Jamestown, Va.
Pocatello (pop. 46,340), city in southeast Idaho.
Podgorny, Nikolai Viktorovich (1903–83), Soviet political leader.
Podiatry, science of disorders and diseases of the feet.
Poe, Edgar Allan (1809–49), U.S. short-story writer, poet, and critic, famous for his tales of mystery and the macabre, such as “The Murders in the Rue Morgue” (1841) and “The Purloined Letter” (1844), prototypes of the detective story, and “The Fall of the House of Usher” (1839).
Poet laureate, royal appointment held by a British poet who writes poems for state occasions.
Poetry, meaningful arrangement of words into an imaginative or emotional discourse, with a strong rhythmic pattern. The language, seeking to evoke image and idea, uses imagery and metaphor. Rhyme or alliteration may also be important elements. The length of poems varies from brief lyric poems to long narrative poems or epic poems, with the length and scope of the novel. The kind of forms and devic…
Pogrom (from Russian for “devastation” or “riot”), term for the officially condoned mob attacks on Jewish communities in Russia between 1881 and 1921.
Pohnpei, island in the western Pacific Ocean.
Poincaré, Jules Henri (1854–1912), French mathematician, cosmologist, and scientific philosopher, best known for his many contributions to pure and applied mathematics and celestial mechanics.
Poincaré, Raymond (1860–1934), French politician, three times premier (1912–13, 1922–24, 1926–29) and president (1913–20).
Poinciana, any of various tropical flowering trees in the pea family.
Poinsettia, name for a variety of spurges (genus Euphorbia) with colorful, attractive bracts (whorled leaves that enclose the small flower).
Point Four Program, technical assistance plan for less developed nations proposed by President Harry Truman in his inaugural address, Jan. 1949, so named because it was the fourth point in the speech.
Pointer, large hunting dog.
Pointillism, painting technique in which tiny paint dots of color are juxtaposed on a canvas to build up the form.
Poison, substance that causes illness or death when it is eaten or absorbed into the body.
Poison gas See: Chemical and biological warfare.
Poison ivy, vine that grows plentifully in the United States and southern Canada.
Poison oak, vine similar to poison ivy and poison sumac.
Poison sumac See: Sumac.
Poisonous plant, any plant that produces harmful effects to people or animals.
Poitier, Sidney (1927– ), U.S. film and stage actor.
Poitiers, Battle of, English victory in the Hundred Years' War, fought in 1356, near Poitiers in west-central France.
Poker, card game whose earliest forms date back to 520 in Europe, developing into bet-and-bluff games like brag in England, pochen (“bluff’) in Germany, and poque in France.
Pokeweed (Phytolacca americana), tall, herbal plant belonging to the pokeweed family.
Poland, former communist state in central Europe. Poland is situated on the Baltic Sea and borders Russia, Lithuania, Byelorussia, Ukraine, Slovakia, Czech Republic and Germany. The land is generally low, with about 90% of it less than 1,000 ft/305 m above sea level, but in the south are the peaks of the Sudeten and Carpathian mountains, forming a natural border with Czech Republic. Poland&…
Polanyi, John Charles (1929– ), Canadian chemist.
Polar bear, large (up to 1,650 lb/750 kg), white-furred, arctic bear (Thalarctos maritimus).
Polaris See: North Star.
Polarized light, light that exhibits unmixed properties (a particular vibration) in a given direction at a right angle to the line of propagation.
Pole vault, sporting event in which an athlete jumps over a crossbar using a pole to push him- or herself off the ground.
Polecat, small carnivore of the weasel family (Mustela putorius), found throughout northern and central Europe.
Polestar See: North Star.
Police, civil body charged with maintaining public order and protecting persons and property from unlawful acts.
Polio See: Poliomyelitis.
Poliomyelitis, or infantile paralysis, viral disease causing muscle paralysis as a result of direct damage to motor nerve cells in the spinal cord.
Polish, West Slavic language, the official and literary language of Poland.
Polish Corridor, strip of Polish land about 25–65 mi (40–105 km) wide and 90 mi (145 km) long.
Polish Succession War See: Succession wars.
Polishing See: Grinding and polishing.
Politburo, in the former USSR, permanent secretariat of top political officials, first formed in 1917, that dominated the Central Committee of the Soviet Communist Party.
Political convention, gathering at which political parties nominate their candidates for president and vice president of the United States.
Political party, body or organization that puts forward candidates for public office and contends for power in elections.
Political science, study of government and political institutions and processes.
Polk, James Knox (1795–1849), 11th president of the U.S. Polk was elected on a pledge to extend the nation's existing territory. During his presidency, the United States—in accordance with the doctrine of “manifest destiny”—expanded across the entire continent and, as part of that expansion, fought the Mexican War. Polk graduated from the University of Nor…
Polk, Leonidas (1806–64), first bishop of Louisiana (1841–61).
Poll See: Public opinion.
Poll tax, tax collected from every adult in a community.
Pollack See: Pollock.
Pollaiuolo, Antonio Del (1429?–98), Italian painter, sculptor, and goldsmith.
Pollen, fine yellow powder produced in the male part of flowers and in the male cone of conifers (cone-bearing plants).
Pollination, in plants, the transfer of pollen from the male stamen of aflower to the female pistil of the same or another flower for fertilization.
Pollinosis See: Hay fever.
Polliwog See: Tadpole.
Pollock (Pollachius virens), fish belonging to the codfish family.
Pollock, Jackson (1912–56), U.S. painter, leader of abstract expressionism.
Pollution See: Environmental pollution.
Pollux See: Castor and Pollux.
Polo, game played on horseback (polo ponies), with a ball and mallets.
Polo, Marco (1254?–1324?), Venetian explorer famous for his overland journey to China (1271–95).
Polonium, chemical element, symbol Po; for physical constants see Periodic Table.
Polyandry See: Polygamy.
Polychlorinated biphenyl (PCB), any of several compounds formed by substituting hydrogen (H) atoms in biphenyl (C6H5C6H5) with chlorine (C1) atoms.
Polyclitus, name of 2 Greek sculptors.
Polyester, any of several strong, light synthetic products made from chemical substances derived from petroleum.
Polyethylene See: Plastic.
Polygamy, marriage in which a man has more than one wife at one time (polygyny), or a woman has more than one husband (polyandry).
Polygon, closed plane figure bounded by three or more straight lines, such as triangles (3 sides), pentagons (5 sides), and dodecagons (12 sides).
Polyhedron, three-dimensional figure bounded by 4 or more polygon sides.
Polymer, substance composed of very large molecules (macromolecules) built up by repeated linking of small molecules (monomers).
Polymerization, chemical process in which many small molecules, called monomers, are joined together to produce a large molecule, called a polymer.
Polymorphism, in zoology, the existence of more than two forms or types of individual within the same species of animal.
Polynesia See: Pacific Islands.
Polyphony (Greek, “many sounds”), music made up of several independent melodic lines linked harmonically through counterpoint.
Polytheism, belief in many gods, as opposed to monotheism or dualism; characteristic of most religions, notably Hinduism and Greek and Roman religion.
Pomegranate, family of tropical shrubs and small trees native to Asia and India and cultivated in the United States.
Pomerania, region in north-central Europe, south of the Baltic Sea.
Pomeranian, small dog, weighing from 3 to 7 lbs (1.4 to 3.2 kg) and standing approximately 6 in (15.3 cm) tall at the shoulder.
Pompadour, Marquise de (1721–64), mistress of King Louis XV of France from 1745.
Pompano, any of several saltwater fishes belonging to the jack family.
Pompeii, ancient Roman city in southern Italy, buried by an eruption of Mt.
Pompey the Great (106–48 B.C.), Roman general and political leader.
Pompidou, Georges Jean Raymond (1911–74), president of France from 1969 to 1974.
Ponape See: Pohnpei.
Ponce (pop. 161,700), city in Puerto Rico.
Ponce de León, Juan (c.14060–1521), Spanish discoverer of Florida.
Ponchielli, Amilcare (1834–86), Italian opera composer.
Pond, still body of water smaller than a lake.
Pond lily See: Water lily.
Pondweed, name for freshwater plants (genus Potamogeton) that sometimes clog streams and ponds.
Ponomarev, Boris Nikolaevich (1905– ), prominent official in Soviet Communist Party.
Ponselle, Rosa Melba (1897–1981), U.S. soprano, born Rosa Ponzillo.
Ponta Delgada (pop. 21,800), city on Saö Miguel Island, the largest of the Portuguese Azores islands.
Pontiac (1720–69), chief of the Ottawa Indians.
Pontiac (pop. 76,715), city in southeastern Michigan.
Pontifex, high priest of ancient Rome, one of the 16 members of the Pontifical College presiding over the state religion.
Pontiff See: Pope.
Pontine Marshes, swamp region in Italy.
Pontoon bridge, bridge held up by pontoons (flat-bottomed boats), sealed metal tubes, or other floating objects.
Pontus, ancient kingdom in northeastern Asia Minor by the Black Sea.
Pony See: Horse.
Pony express, famous relay mail service between St.
Poodle, breed of intelligent dogs.
Pool See: Billiards.
Poor Richard's Almanac, almanac, written and published by Benjamin Franklin.
Poorwill See: Whippoorwill.
Pop art, modern art movement dating from the mid-1950s, based on images of advertising, commercial illustration, and mass-produced objects.
Popcorn (Zea mays everta), type of corn that opens and puffs open when it is heated.
Pormo, Hozan-speaking tribe living in North California, noted for their intricate basket making.