Pi

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

Pi may also refer to:

Letter Pi (π)

Lower-case π

• Pi, the Greek letter
• Lowercase π:
  • π (film), a 1998 film directed by Darren Aronofsky
  • $\pi(x)\,\!$ (pi function), the prime-counting function
  • Pi bond
  • Osmotic pressure
  • A song from the Kate Bush album Aerial
  • Shorthand for pion
  • A men's fragrance from Givenchy
  • The symbol for political life used in Boethius' Consolation of Philosophy
• Uppercase Π:
  • The product symbol
  • $\Pi(x)\,\!$ (Pi function), the Gamma function when offset to coincide with the factorial
    • $\pi(x)\,\!$, the reciprocal of the Pi function

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", a song from the Hard 'n Phirm album Horses and Grasses; the song ends at 3:14
• Pi, a member of Team Robo in Sega Soccer Slam
• Pi, a fictional character in the novel Life of Pi
• Pi County, county in Sichuan, China