Pi () is a mathematical constant equal to a circle's circumference divided by its diameter. Pi, π or Π may also refer to:

Language and typography

Pi (letter) Pi (; Ancient Greek or , uppercase Π, lowercase π, cursive ϖ; ) is the sixteenth letter of the Greek alphabet, representing the voiceless bilabial plosive . In the system of Greek numerals it has a value of 80. It was derived from the Phoeni ...

, the 17th letter of the Greek alphabet * Pi characters, uncommon characters in typesetting * Pi font, a term for some kinds of

dingbat In typography, a dingbat (sometimes more formally known as a printer's ornament or printer's character) is an ornament, specifically, a glyph used in typesetting, often employed to create box frames (similar to box-drawing characters), or a ...

fonts *

Pali Pāli (, IAST: pāl̤i) is a Classical languages of India, classical Middle Indo-Aryan languages, Middle Indo-Aryan language of the Indian subcontinent. It is widely studied because it is the language of the Buddhist ''Pali Canon, Pāli Can ...

, an Indo-Aryan language (ISO 639-1 code: pi)

Places

* Pi (state), an ancient state during China's Zhou dynasty * Pi, Catalonia, a village of Bellver de Cerdanya, Spain * Pi County, Sichuan province, China * Pi Islands, Palmer Archipelago, Antarctica

People

Given name

* Pi de Bruijn (born 1942), Dutch architect * Pi O or П. O. (born 1951), Greek-Australian anarchist poet * Pi Schwert (1892–1941), American baseball player and politician * Pi Vèriss, Dutch songwriter and composer

Stage name

* Pi (entertainer), American drag performer

Surname

Bi (surname) Bi () is a Chinese surname. It is listed 76th in the Song dynasty classic text, the ''Hundred Family Surnames''.K. S. Tom.

989 Year 989 ( CMLXXXIX) was a common year starting on Tuesday of the Julian calendar. Events By place Byzantine Empire * Emperor Basil II uses his contingent of 6,000 Varangians to help him defeat Bardas Phokas (the Younger), who suffe ...

(1989). Echoes from Old China: Life, Legends and Lore of the Middle Kingdom. University of Hawaii Press. . Origin ...

(), romanized as Pi in Wade–Giles * Pi (surname) (), a Chinese surname * Enric Pi (born 1983), Catalan footballer * Francesc Pi i Margall (1824–1901), Catalan politician * Jordi Sabater Pi (1922–2009), Catalan primatologist and ethologist * Meritxell Mateu i Pi (born 1966), Andorran diplomat * Ot Pi (born 1970), Catalan mountain bike trials rider * Pedro Pi (1899–1970), Spanish sailor * Renzo Pi Hugarte (1934–2012), Uruguayan anthropologist

Arts, entertainment, and media

Fictional characters

* Pi (.hack), in the multimedia franchise ''.hack//G.U.'' * Pi, in both: ** '' Life of Pi'', a 2001 novel, and ** ''Life of Pi'' (film), a 2012 adaptation * Pi, a member of Team Robo in '' Sega Soccer Slam'' * Pi, in the 2006 animated film '' Shark Bait'' and the 2012 sequel ''The Reef 2: High Tide''

Music

* Pi (instrument), several traditional Thai reed instruments * "π", a song by Kate Bush from '' Aerial'' * "Pi", a song by Hard 'n Phirm from '' Horses and Grasses'' * "Pi", a song by J. Cole from '' Might Delete Later'' * "Pi", a song by Käptn Peng & Die Tentakel von Delphi from ''

Das nullte Kapitel ''Das nullte Kapitel'' is a 2017 German hip-hop album by Käptn Peng & Die Tentakel von Delphi. It is the second album by the band, following 2013's '' Expedition ins O''. It was published by the independent label Kreismusik. The album, as wi ...

'' * Pi Recordings, a record label

Other arts, entertainment, and media

* ''Pi'' (film), a 1998 film directed by Darren Aronofsky * ''P.I.'' (TV series), a 2017 Singaporean 1series * '' Pi magazine'', a student publication of the University College London Union * Pi Studios, a video game developer

Science and mathematics

Chemistry and biochemistry

* π, a measure of

nucleotide diversity Nucleotide diversity is a concept in molecular genetics which is used to measure the degree of polymorphism (biology), polymorphism within a population. One commonly used measure of nucleotide diversity was first introduced by Masatoshi Nei, Nei a ...

* Π or

Osmotic pressure Osmotic pressure is the minimum pressure which needs to be applied to a Solution (chemistry), solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a soluti ...

* P_i, an inorganic

phosphate Phosphates are the naturally occurring form of the element phosphorus. In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthop ...

group *

Isoelectric point The isoelectric point (pI, pH(I), IEP), is the pH at which a molecule carries no net electric charge, electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH(I). Howe ...

(pI), the pH at which a particular molecule carries no net electrical charge in the statistical mean *

Pi bond In chemistry, pi bonds (π bonds) are covalent chemical bonds, in each of which two lobes of an orbital on one atom overlap with two lobes of an orbital on another atom, and in which this overlap occurs laterally. Each of these atomic orbital ...

, a chemical bond

Logic and computer science

* Π, the symbol for maxterm notation in Karnaugh mapping *

Raspberry Pi Raspberry Pi ( ) is a series of small single-board computers (SBCs) developed in the United Kingdom by the Raspberry Pi Foundation in collaboration with Broadcom Inc., Broadcom. To commercialize the product and support its growing demand, the ...

, a single-board computer developed by Raspberry Pi Foundation; also known as Pi

Mathematics

* , a glyph representing the product of a sequence of terms * , a set in the

arithmetical hierarchy In mathematical logic, the arithmetical hierarchy, arithmetic hierarchy or Kleene–Mostowski hierarchy (after mathematicians Stephen Cole Kleene and Andrzej Mostowski) classifies certain sets based on the complexity of formulas that define th ...

* , a set in the

analytical hierarchy Analytic or analytical may refer to: Chemistry * Analytical chemistry, the analysis of material samples to learn their chemical composition and structure * Analytical technique, a method that is used to determine the concentration of a chemica ...

* , a set in the

polynomial hierarchy In computational complexity theory, the polynomial hierarchy (sometimes called the polynomial-time hierarchy) is a hierarchy of complexity classes that generalize the classes NP and co-NP. Each class in the hierarchy is contained within PSPACE. ...

* (Pi function), the

Gamma function In mathematics, the gamma function (represented by Γ, capital Greek alphabet, Greek letter gamma) is the most common extension of the factorial function to complex numbers. Derived by Daniel Bernoulli, the gamma function \Gamma(z) is defined ...

when offset to coincide with the factorial * , the complete elliptic integral of the third kind * , the th

homotopy group In mathematics, homotopy groups are used in algebraic topology to classify topological spaces. The first and simplest homotopy group is the fundamental group, denoted \pi_1(X), which records information about loops in a space. Intuitively, homo ...

of * , the fundamental ''n''-groupoid of ** , the

fundamental groupoid In algebraic topology, the fundamental groupoid is a certain topological invariant of a topological space. It can be viewed as an extension of the more widely-known fundamental group; as such, it captures information about the homotopy type of a to ...

of * , the th cohomotopy set of * , a notation for the scalar projection onto the ''n''-th component * -calculus, a process calculus *

Prime-counting function In mathematics, the prime-counting function is the function counting the number of prime numbers less than or equal to some real number . It is denoted by (unrelated to the number ). A symmetric variant seen sometimes is , which is equal ...

or *

\pi

, the population proportion in statistics

Physics

Pion In particle physics, a pion (, ) or pi meson, denoted with the Greek alphabet, Greek letter pi (letter), pi (), is any of three subatomic particles: , , and . Each pion consists of a quark and an antiquark and is therefore a meson. Pions are the ...

or π, a subatomic particle

Other uses

* Pi (prefix symbol), or pebi, in computing * Π, for plaintiff, in legal shorthand * Π, stands for Pierikos F.C. kit logo *

Pi Day Pi Day is an annual celebration of the mathematical constant (pi). Pi Day is observed on March 14 (the 3rd month) since 3, 1, and 4 are the first three significant figures of , and was first celebrated in the United States. It was founded i ...

, March 14 (3/14 in the US) * Principal investigator, a lead researcher *

Private investigator A private investigator (often abbreviated to PI; also known as a private detective, an inquiry agent or informally a wikt:private eye, private eye) is a person who can be hired by individuals or groups to undertake investigatory law services. ...