# Pi (disambiguation)

Pi (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), the 17th letter of 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

### Stage name

* Pi (entertainer), American drag performer

### 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", a song by J. Cole from Might Delete Later
* 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 developed by Raspberry Pi Foundation; also known as Pi

### Mathematics

* Π, a glyph representing the product of a sequence of terms
* Π$^0$ $_n$, a set in the arithmetical hierarchy
* Π$^1$ $_n$, 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$_n$(X), the fundamental n-groupoid of X
** Π(X), the fundamental groupoid of X
* π$^n$(X), the nth cohomotopy set of X
* π$_n$, a notation for the scalar projection onto the n-th component
* π-calculus, a process calculus
* Prime-counting function or π(x)
* $\pi$, 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