Π or π (or in English, "**pi**") is the 16^{th} letter of the Greek alphabet.

The upper case form, Π , means:

- Π product of a series (mathematics)

The lower case form, π , means:

`π`the ratio of a circle's circumference to its diameter, which is 3.14159... (math)`π`population percentage (statistics)- π pion (physics)

As the top of this e2node indicates, pi is also an Everythingite.