Definition of pi
(Entry 1 of 5)
1
: the 16th letter of the Greek alphabet — see Alphabet Table
2a
: the symbol π denoting the ratio of the circumference of a circle to its diameter
b
: the ratio itself : a transcendental number having a value rounded to eight decimal places of 3.14159265
pi
noun (2)
variants:
or less commonly pie
plural pies
Definition of pi (Entry 2 of 5)
1
: type that is spilled or mixed
2
: a pi character or matrix
pi
verb
variants:
or less commonly pie
pied; piing or pieing
Definition of pi (Entry 3 of 5)
: to spill or throw (type or type matter) into disorder
: to become pied
pi
adjective
variants:
or less commonly pie
Definition of pi (Entry 4 of 5)
1
: not intended to appear in final printing
pi lines
2
: capable of being inserted only by hand
pi characters
PI
abbreviationDefinition of PI (Entry 5 of 5)
1
Philippine Islands
2
private investigator
3
programmed instruction
Test Your Vocabulary
Great Words for Scrabble
-
- Which of the following Q-without-U words means the number five in cards or dice?

Can you spell these 10 commonly misspelled words?
TAKE THE QUIZ
A daily challenge for crossword fanatics.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridged
Share pi
Time Traveler for pi
The first known use of pi was in the 15th century
See more words from the same century