Pi (disambiguation)

Pi, or π is the mathematical constant equal to a circle's circumference divided by its diameter.

Pi, PI, π or Π may also refer to:

Letter Pi (π)

• Pi (letter), the Greek letter
• Lowercase π:
  • π(x) (pi function), the prime-counting function
  • π_n(X) the nth homotopy group of X
  • Pi bond, a chemical bond
  • Parallax in astrometry, especially annual parallax.
  • A song from the Kate Bush album Aerial
  • pion, a subatomic particle
  • A men's fragrance from Givenchy
  • The symbol for political life used in Boethius' Consolation of Philosophy
  • Pi-calculus, a process calculus.
• Uppercase Π:
  • Osmotic pressure
  • The product symbol
  • Π(x) (Pi function), the Gamma function when offset to coincide with the factorial
    • π(x), the reciprocal of the Pi reciprocal
  • $\Pi^0_n$, a set in the Arithmetical hierarchy
  • $\Pi^1_n$, a set in the Analytical hierarchy
  • $\Pi^P_i$, a set in the Polynomial hierarchy

Pi as a word

• Pi (instrument)
• Pi (.hack), a fictional character from the multimedia franchise .hack//G.U.
• Pi Magazine
• Pi Recordings, a record label
• Pi, Catalonia, a town in Catalonia, Spain
• Pi County in Sichuan, China
• Pi (film), a 1998 film directed by Darren Aronofsky
• Pi Studios, a video game developer
• Pi (state) a vassal state in Zhou Dynasty China (1046–256 BCE)
• "Pi", a song from the Hard 'n Phirm album Horses and Grasses
• Pi, a member of Team Robo in Sega Soccer Slam
• Pi, a fictional character in the novel Life of Pi
• PI System data analysis software, made by OSIsoft
• Pi Islands

PI as an abbreviation

Science

• Parental Investment in biology
• Primary immunodeficiency
• An inorganic phosphate group (as P_i)
• The isoelectric point (as pI)
• Phosphatidylinositol
• Propidium iodide
• Polarity item in linguistics
• Polyimide
• Ponderal Index
• Potential instability in meteorology
• Protease inhibitor (pharmacology), class of drugs used to treat or prevent infection by viruses, including HIV and Hepatitis C
• Protease inhibitor (biology), molecules that inhibit the function of proteases
• Pistillata a gene that influences the development of flowers in the ABC Model of Flower Development
• Prediction interval in statistics
• Paternity Index

Companies and organizations

• Parents for Inclusion
• Perimeter Institute for Theoretical Physics
• Privacy International
• Pasteur Institute
• Sun Air (Fiji) (IATA airline code: PI)

Political parties

• Independent Party (Uruguay) (Spanish: Partido Independiente)
• Intransigent Party (Spanish: Partido Intransigente), Argente political party

Professional occupations

• Photographic interpreter, an aerospace and strategic reconnaissance term
• In legal shorthand, it refers to a plaintiff
• Personal injury attorney
• Principal investigator, the lead scientist in a project
• Private investigator
• Permanent injunction

Computing

• Page impressions, an online advertising term
• Pebi, a Binary prefix
• Programmed instruction
• Provider Independent Address Space
• Processing Instruction, SGML and XML node type
• Raspberry Pi, a miniature motherboard

Other

• Pass interference in American football
• Parameter indicator, in ISO standards
• People's Initiative
• Profitability index
• Personal injury
• The Philippines (from "Philippine Islands")
• PI controller, a concept in automation and control engineering
• Piauí, a state in Brazil
• Poison Idea, American hardcore punk band
• Public intoxication
• Seattle Post-Intelligencer
• Philippine Idol
• Primitive Instinct
• Proforma invoice
• Plasticity index
• Prison Industry, as often coined on the Fox hit series Prison Break
• Marine Corps Recruit Depot Parris Island
• Philippine Islands
• Partit per la Independència, a short lived political party in Catalonia of the 1990s

See also

• P (disambiguation)
• Pie (disambiguation)