The upper-case letter Π is used as a symbol for:
- In mathematics, the product operation.
- In textual criticism, Codex Petropolitanus, a 9th century, uncial codex of the Gospels, now located in St. Petersburg, Russia.
- In economics, profit.
- In mathematics, the constant pi, which is the ratio of the circumference to the diameter of a circle.
- In number theory, the function π(x) is the number of primes that are less than or equal to x.
- In particle physics, π0, π+ and π- are three forms of pi meson.