Peristalsis In the digestive tract, the muscularis externa propels the material along the alimentary canal. During a peristaltic movement, the circular muscles contract behind the digested material; then a contraction of the longitudinal muscle follows which pushes the digested food further along the esophagus.
	Peristome The word peristome is derived from the Greek language for 'around a mouth', and is a term used to describe various structures in plants that surround an opening to an organ. In bryophyte mosses, the peristome is a specialized structure in the sporangium that allows for gradual spore discharge, instead of releasing them all at once.
	Peristyle In Roman architecture a peristyle is a columned porch or open colonnade in a building that surrounds a court that may contain an internal garden. "Tetrastoon" is another name for this feature. In the Christian ecclesiastical architecture that developed from Roman precedents, a basilica, such as Old St Peter's in Rome, would stand behind a peristyle forecourt that sheltered it from the street.
	Perm Perm is a city in and administrative center of Perm Krai, Russia. It is situated on the banks of the Kama River, at the foot of the Ural Mountains. Its geographical location is . Perm is one of the largest and List of cities and towns in Russia by population cities of Russia.
	Permafrost In geology, permafrost or permafrost soil is a thermal condition where ground material stays at or below 0Celsius for two or more years. Permafrost is where water is permanently frozen in the soil resulting in minimal or no plant growth. The presence of ice is not necessary, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts excess of the potential hydraulic saturation of the ground material.
	Permanent wave A permanent wave, commonly called a perm, is the chemical treatment of hair to produce curls. In cosmetology, it is termed a type of curl reformation. Humans have been attempting to add curl to straight hair for thousands of years. The ancient ancient Egypt did this by wrapping their hair around wooden sticks; slathering it with mud from hot springs; letting it bake dry in the sun and then removing the mud.
	Permanent Waves Permanent Waves is the seventh studio album by the Canada rock band Rush, released January 1, 1980. The album was recorded at Le Studio, Morin Heights, Quebec, and was mixed at Trident Studios in London, United Kingdom. Permanent Waves marks a distinct transition into more accessible, radio-friendly numbers and consequently, a significant expansion in the band's record sales with perennial favorites such as "The Spirit of Radio" and "Freewill" seeing quite a fair bit of radio air
	Permeation Permeation, in physics, is the penetration of a substance through a solid. Primum mobile is the concentration gradient. Permeability is tested by permeation measurement.
	Pernambuco Pernambuco |- | align=center colspan=2 | | align=center width=135 | |} |- |colspan="2" style="text-align:center;" | Flags of Brazilian states |- | align=center colspan=2 | Pernambuco is a States of Brazil of Brazil, located in the Northeast Region, Brazil.
	Peromyscus The genus Peromyscus, contains species commonly referred to as deer mice., This is a genus of New World mouse only distantly related to the common house mouse, Mus musculus. The most common species of deer mouse in the continental United States are two closely related species, Peromyscus maniculatus, and Peromyscus leucopus.
	Peromyscus maniculatus Peromyscus maniculatus is rodent native to North America. It is most commonly called a Deer Mouse and is fairly widespread across the continent with the major exception being the southeast United States and the far north. This mouse is a known carrier of hantavirus, which can be transmitted to humans.
	Peroxidase A peroxidase is an enzyme, which may contain heme, that catalyzes a reaction of the form: For many of these enzymes the optimal substrate is hydrogen peroxide, but others are more active with organic hydroperoxides such as lipid peroxides. The nature of the nucleophile is very dependent on the structure of the enzyme.
	Perpendicular In geometry, two line are considered perpendicular if one falls on the other in such a way as to create two congruence angles. The term may be used as a noun or adjective. Thus, referring to Figure 1, the line AB is the perpendicular to CD through the point B.
	Perpetual calendar A perpetual calendar is a calendar which is good for a span of many years, such as the Runic calendar.
	Perpetual motion Perpetual motion refers to a condition in which an object continues to move indefinitely without being driven by an external source of energy. The term is commonly used to refer to machines which display this phenomenon. In the macroscopic world, perpetual motion is not generally considered to be possible.
	Perphenazine Perphenazine is a typical antipsychotic psychoactive drug. Chemically, it is classified as a piperazinyl phenothiazine. It has been in clinical use for decades. Perphenazine is 10 to 15 times as potent as chlorpromazine; that means perphenazine is a highly potent antipsychotic.
	Perry Perry or pear cider is an alcoholic beverage made of fermentation pear juice. It is similar to cider, in that it is made using a similar process and often has a similar ethanol content, around 8% alcohol by volume. Perry has been common for centuries in Britain, particularly the West Country and Wales; and France, especially Normandy and Anjou.
	Perry Mason Perry Mason is a fictional defense attorney who originally appeared in detective fiction by Erle Stanley Gardner. He appeared in over 80 novels and short stories, most of which involved his client being put on trial for murder. Typically, he was able to establish his client's innocence by dramatically demonstrating the guilt of another character.
	Persea Persea is a genus of about 150 species of evergreen trees belonging to the laurel family, Lauraceae. The best-known member of the genus is the Avocado P. americana, widely cultivated in subtropical regions for its large, edible fruit. They are medium-size trees, 15-30 m tall at maturity.
	Persephone In Greek mythology, Persephone was the queen of the Greek Underworld, the Kore or young maiden, and the daughter of Demeter and Zeus. Persephone is her name in the Ionic Greek of Epic poetry literature. In other dialects she was known under various other names: Persephassa, Persephatta, or simply Kore .
	Persepolis Persepolis was an ancient ceremonial capital of the second Iranian dynasty, the Achaemenid Empire, situated some 70 km northeast of modern city of Shiraz, Iran, not far from where the small river Pulwar flows into the Kur. To the ancient Persians, the city was known as Parsa, meaning the city of Persians, Persepolis being the Greek interpretation of the name 17.70 Persepolis was the capital of the Persian kingdom.
	Perseus Perseus, Perseos, or Perseas, the legendary founder of Mycenae and of the Mycenae there, was the first of the mythic heroes of Greek mythology whose exploits helped establish the hegemony of Zeus and the Twelve Olympians in the mainland of Greece.
	Persian Empire The Persian Empire was a series of historical empires that ruled over the Greater Iran and beyond. Generally, the earliest entity considered a part of the Persian Empire is Persia's Achaemenid dynasty , a united Aryan kingdom that originated in the region now known as Fars Province of Iran and was formed under Cyrus the Great.
	Persian Gulf The Persian Gulf , in the Middle East region, is an extension of the Gulf of Oman located between Iran and the Arabian Peninsula. The Persian Gulf was the focus of the Iraq-Iran War that lasted from 1980 to 1988, with each side attacking the other's oil tankers.
	Persian Walnut The Persian Walnut is a walnut native from the Balkans in southeast Europe east through southwest and central Asia and the Himalaya to southwest China. It is a large deciduous tree attaining heights of 25-35 m, and a trunk up to 2 m diameter, commonly with a short trunk and broad crown, though taller and narrower in dense forest competition.
	Persimmon Persimmon most commonly refers to the edible fruit borne by some species of the genus Diospyros. They are also known as kaki, sharon fruit, black sapote, mabolo or velvet-apple, date-plum, Texas persimmon and American persimmon. The term is also used to refer to the trees bearing the fruit.
	Persona A persona, in the word's everyday usage, is a social role, or a character played by an actor. The word derives from the Latin for "mask" or "character", derived from the Etruscan word "phersu", with the same meaning.
	Personal personal could refer to * personal identity; * a personal advertisement; * an person's Ego, super-ego, and id or self image, interests or Goals; * a personal problem; * personal involvement; * a trademark belonging to Sony * Personal, Paraguayan mobile phone network
	Personal computer A personal computer is usually a microcomputer whose price, size, and capabilities make it suitable for personal usage. The term was popularized by Apple Computer with the Apple II in the late-1970s and early-1980s, and afterwards by IBM with the IBM PC. History
	Personal digital assistant Personal Digital Assistants are handheld devices that were originally designed as personal organisers, but became much more versatile over the years. The many uses and tasks of a basic PDA include many features: calculating, use as a clock and calendar, playing computer games, accessing the Internet, sending and receiving E-mails, use as a radio or stereo, video recording, recording notes, use as an address book, and use as a spreadsheet.
	Personal organizer A personal organizer, day planner, or personal planner is a small book usually containing a calendar, address book, and ruled pages in which one may record notes. Paper-and-binder personal organizers are increasingly being supplanted by electronic personal digital assistants and personal information manager software; some personal organizers attempt to bridge the gap by featuring holders for PDAs.
	Personality test A personality test aims to describe aspects of a person's character that remain stable throughout a person's lifetime. A model of personality were first posited by Ancient Greece Philosophy/physician Hippocrates. The 20th century heralded a new interest in defining and identifying separate personality types, in close correlation with the emergence of the field of psychology.
	Personification Personification is a figure of speech that gives animals and objects human traits and qualities. These attributes may include sensations, emotions, desires, physical gestures ,expressions, and powers of speech, among others. As a figure of speech it has a very long history; its Greek name is prosopopoeia.
	Persoonia Persoonia is a genus of 98 species of shrubs and small trees in the plant family Proteaceae. In the eastern states of Australia, they are commonly known as Geebungs, while in Western Australia and South Australia they go by the common name Snottygobbles.
	Persuader Persuader is a Sweden band that was formed in 1997. They have since released three full length albums: The Hunter, Evolution Purgatory, and When Eden Burns. They have a pretty unusual sound but similar bands include early Blind Guardian, Iron Savior, and Nocturnal Rites, although Persuader includes a little bit of thrash metal as well.
	Peru Peru, officially the Republic of Peru, is a country in western South America, bordering Ecuador and Colombia to the north, Brazil to the east, Bolivia to the south-east, Chile to the south, and the Pacific Ocean to the west. In addition to being known as the cradle of the Inca empire, Peru is the home of many amerindians.
	Peshawar Peshawar literally means City on the Frontier in Persian language and is known as Pai-khawar in Pashto. It is the provincial capital of Pakistan's North-West Frontier Province. Located on the edge of the Khyber Pass, Peshawar is the commercial, economic, political and cultural capital of the Pakistani frontier and, particularly, of the Pashtuns.
	Peshmerga Peshmerga, pesh merga, peshmarga or peshmerge Kurdish: psmerge) is the term used by Kurds to refer to armed Kurdish fighters. Literally meaning "those who face death" the peshmerga forces of Kurdistan have been around since the advent of the Kurdish independence movement in the early 1920s, following the collapse of the Ottoman Empire and Qajar empires which had jointly ruled over the area always known as Kurdistan.
	Pessimism Pessimism, from the Latin pessimus , denotes a belief that the experienced world is the worst possible. It describes a general belief that things are bad, and tend to become worse; or that looks to the eventual triumph of evil over Goodness and value theory; it contrasts with optimism, the contrary belief in the goodness and betterment of things generally.
	Pesticide The U.S Environmental Protection Agency defines a pesticide as "any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest ". A pesticide may be a chemical substance or biological agent used against pest s including insects, plant pathogens, weeds, mollusks, birds, mammals, fish, nematodes and microbes that compete with humans for food, destroy property, spread disease or are a nuisance.
	Pesto Pesto is an Italy sauce that originates in the Liguria region of Northern Italy, specifically in the city of Genoa, although at least one other well-known variant exists: pesto alla siciliana, a sauce from Sicily that replaces the basil of Genovese pesto with tomato.
	Pet A pet is an animal kept for companionship and enjoyment, as opposed to livestock, laboratory animals, working animals or sport animals, etc who are kept for economic reasons or to perform specific jobs. The most popular pets are noted for their loyal or playful characteristics, for their attractive appearance, for their song.
	Petal A petal, regarded as a highly modified leaf, is one member or part of the corolla of a flower. It is the inner part of the perianth that comprises the sterile parts of a flower and consists of inner and outer tepals. These tepals are usually differentiated into petals and sepals.
	Petard A petard was a Middle Ages term for a small bomb used to blow up gates and walls when breaching fortifications. Petard mortar was also the name of the demolition weapon fitted to the Churchill tank tank. It was mortar of 290 mm bore known to its crews as the "flying dustbin" from the projectile: an unaerodynamic 20 kg charge sufficient to demolish many bunkers and earthworks and even disable a Tiger tank which could be fired up to 100 m.
	Petaurus The genus Petaurus contains flying phalangers or wrist-winged gliders, a group of arboreal marsupials. There are six species, Sugar Glider, Squirrel Glider, Mahogany Glider, Northern Glider, Yellow-bellied Glider and Biak Glider, and all are native to Australia.
	Pete Seeger Peter Seeger almost universally known as "Pete Seeger", is a folk singer and Politics activist. As a member of the Weavers, he had a string of hits, including a 1949 recording of Leadbelly's "Goodnight Irene" that topped the charts for 13 weeks in 1950. He was a major contributor to Folk music and pioneer of Protest song in the 1950s and the 1960s.
	Peter Abelard Pierre Ablard or Abailard was a French Scholasticism philosopher and logician. The story of his affair with his student, Heloise has become legendary.
	Peter Carl Fabergé Peter Carl Faberg original name Carl Gustavovich Faberg was a Russian jewellery, best known for the fabulous Faberg eggs, made in the style of genuine Easter eggs, but using precious metals and gemstones rather than more mundane materials. He was born in St. Petersburg to the jeweller Gustav Faberg and his Denmark wife Charlotte Jungstedt.
	Peter Cooper Peter Cooper was an United States industrialist, inventor and philanthropist.
	Peter Lorre Peter Lorre , born Ladislav Lwenstein, was a stage and screen actor of Austria-Hungary descent especially known for playing roles with sinister overtones in Hollywood crime films and mysteries.
	Peter O'Toole Peter Seamus O'Toole is an Republic of Ireland-born film and stage actor who was raised in England in the Yorkshire city of Leeds. He was born in Connemara, County Galway, Ireland and spent most of his life in Great Britain until returning to Ireland at the height of his fame in 1963.
	Peter Pan Peter Pan is a fictional character created by Scotland novelist and playwrighter, J. M. Barrie , as well as the title of a play and novel based on the character. A mischievous little boy who refuses to manhood, Peter Pan spends his never-ending childhood adventuring on the small island of Neverland as leader of his gang, the Lost Boys; The twins, Slightly, Tootles, Curly and Nibs.
	Peter Paul Rubens Peter Paul Rubens was the most popular and prolific Flemings and European painter of the 17th century. He was the proponent of an exuberant Baroque style which emphasized movement, colour, and sensuality.
	Peter Sellers Richard Henry "Peter" Sellers, Order of British Empire was an England comedian, actor, and performer, who came to prominence on the BBC radio series The Goon Show and later became a film star. He is regarded by many as one of the best comedy actors of his generation.
	Peter Stuyvesant Peter Stuyvesant served as the last Netherlands Director-General of New Netherland of the colony of New Netherland from 1647 until it was ceded provisionally to the English in 1664. He was a major figure in the early history of New York City. Stuyvesant's accomplishment as director-general included a great expansion for the settlement of New Amsterdam beyond the southern tip of Manhattan.
	Petrarch Francesco Petrarca or Petrarch was an Italy scholar, poet, and early humanist. Petrarch and Dante Alighieri are considered the fathers of the Renaissance.
	Petrel The petrels are seabirds in the bird order Procellariiformes. They occur in four families within that group, which also includes the Albatross family, Diomedeidae. Having a fossil record that extends back at least 60 million years, it is among the older bird groupings, other than the ratites, with distant ties to penguins and loons.
	Petri dish A Petri dish is a shallow glass or plastic cylindrical dish that biologists use to microbiological culture cell s, which can be bacterial, animal, plant, or fungus. It was named after the Germany bacteriologist Julius Richard Petri who invented it in 1877 when working as an assistant to Robert Koch.
	Petrifaction In geology, petrifaction or petrification is the process by which organic material is converted into Rock or a similar substance. It is approximately synonymous with fossil. Petrified wood is the most well known result of this process. The Grotto of the Redemption is the world's largest collection of petrifications and rocks located in one site.
	Petrified Forest National Park Petrified Forest National Park is located in northeastern Arizona, along Interstate 40 between Holbrook, Arizona and Navajo, Arizona. It features one of the world's largest and most colorful concentrations of petrified wood, mostly of the species Araucarioxylon arizonicum.
	Petroleum Petroleum or crude oil is a black, dark brown or greenish liquid found in porous rock formations in the earth. The American Petroleum Institute, in its Manual of Petroleum Measurement Standards , defines it as "a substance, generally liquid, occurring naturally in the earth and composed mainly of mixtures of chemical compounds of carbon and hydrogen with or without other nonmetallic elements such as sulfur, oxygen, and nitrogen."
	Petroleum geology Petroleum geology refers to the specific set of geological disciplines that are applied to the search for hydrocarbons. Sedimentary basin analysis Petroleum geology is principally concerned with the evaluation of seven key elements in sedimentary basins: *Source *Reservoir *Seal
	Petticoat A petticoat or underskirt is an article of clothing for women; specifically an undergarment to be worn under a skirt, dress or sari. The petticoat is a separate garment hanging from the waist. *In historical contexts, petticoat refers to any separate skirt worn with a gown, bedgown, bodice or jacket; these petticoats are not strictly speaking underwear as they were made to be seen.
	Petting zoo A petting zoo features a combination of domestic animals and some wild species that are docile enough to touch and feed. In addition to independent petting zoos, also called children's farms, many general zoos contain a petting zoo. Petting zoos are extremely popular with small children.
	Petty Officer A Petty Officer is a Non-commissioned officer or equivalent in many navy.
	Petunia Petunia is a widely-cultivated genus of flowering plants, in the family Solanaceae. The popular flower got its name from French. In that language, the word "petun" once meant "tobacco". The French adopted the term from a local Indian dialect from the Amazon. Most of the varieties seen in gardens are hybrids.
	Pew A pew is a long bench used for chair of a church congregation. Churches were not commonly furnished with permanent pews before the coming of the Protestant Reformation. The rise of the sermon as a central act of Christianity worship, especially in Protestantism, made the pew an indispensable item of church furniture.
	Pewee The genus Contopus is a group of small to medium-sized insect-eating birds in the Tyrant flycatcher family Tyrannidae. These birds are commonly known as peewees, from the call of one of the more common members of this vocal group. They are generally greyish birds with wing bars that live in wooded areas.
	Pewter Pewter is a metal alloy, traditionally between 85 and 99 percent tin, with the remainder consisting of 1-4 percent copper, acting as a hardener, with the addition of lead for the lower grades of pewter and a bluish tint. Traditionally, there were three grades of pewter: fine, for eatingware, with 96-99 percent tin, and 1-4 percent copper; trifle, also for eating and drinking utensils but duller in appearance, with 92 percent tin, 1-4 percent copper, and up to 4 percent lead; and lay or ley metal, not f
	Peyote Peyote is a small spineless cactus whose native region extends from the southwestern United States through central Mexico. The cactus flowers sporadically, producing small pink fruit, similar in appearance to a chili pepper, which can be very delectable and sweet-tasting when eaten.