General Science

  • noun the ratio of the circumference of a circle to its diameter.


  • noun a Greek letter used in mathematics to indicated the quantity 3.14159. The Ancient Greeks calculated that the circumference of a circle was 2πr (where r is the radius) and that the area of a circle is πr2 but they were not able calculate an exact value for π. They knew it was slightly less than 3 1/7. In fact, π does not have a finite value, being 3.14159… with a series of figures continuing to infinity.


  • An irrational number whose value is approximately 3.14159265358979, although it continues indefinitely in a non-repeating manner. It is used in many calculations. Its symbol is π.

Media Studies

  • noun a pile of printing type that has been mixed up together


  • abbreviation forpica (pc or pi)


  • acronym forpressure index
    (written as PI)