Look up pi, π, or Π in Wiktionary, the free dictionary.

Pi or π 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), in the Greek alphabet
• Pi characters, uncommon characters in typesetting
• Pi font, a term for some kinds of dingbat fonts
• Pali, 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

Surname

• Bi (surname) (Chinese: 毕), romanized as Pi in Wade–Giles
• Pi (surname) (Chinese: 皮), 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 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
• Π or Osmotic pressure
• P_i, an inorganic phosphate group
• Isoelectric point (pI), the pH at which a particular molecule carries no net electrical charge in the statistical mean
• Pi bond, a chemical bond

Logic and computer science

• Π, the symbol for maxterm notation in Karnaugh mapping
• Raspberry Pi, a single-board computer

Mathematics

• Π, a glyph representing the product of a sequence of terms
• Π⁰
  _n, a set in the arithmetical hierarchy
• Π¹
  _n, a set in the analytical hierarchy
• Π^P
  _i, a set in the polynomial hierarchy
• Π(x) (Pi function), the Gamma function when offset to coincide with the factorial
• Π(n, k), the complete elliptic integral of the third kind
• π_n(X), the nth homotopy group of X
• π-calculus, a process calculus
• Prime-counting function or π(x)
• ${\displaystyle \pi }$, the population proportion in statistics

Physics

• Pion 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, March 14 (3/14 in the US)
• Principal investigator, a lead researcher
• Private investigator