PI

noun

1. The 16th letter of the Classical and Modern Greek alphabets and the seventeenth in Old Greek.
2. An irrational and transcendental constant representing the ratio of the circumference of a Euclidean circle to its diameter; approximately 3.14159265358979323846264338327950; usually written π.
3. Metal type that has been spilled, mixed together, or disordered.

verb

1. To spill or mix printing type.

adjective

1. Not part of the usual font character set; especially, non-Roman type or symbols as opposed to standard alphanumeric Roman type.