Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary
1

pi

play
noun \ˈpī\

Definition of pi

plural pis play \ˈpīz\

  1. 1 :  the 16th letter of the Greek alphabet — see alphabet table

  2. 2 a :  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



Origin of pi

Middle Greek, from Greek pei, of Semitic origin; akin to Hebrew pe


First Known Use: 1638

Other Alphabet Terms

Rhymes with pi


2

pi

noun \ˈpī\

Definition of pi

plural pies

  1. 1 :  type that is spilled or mixed

  2. 2 :  a pi character or matrix



Variants of pi

also pie \ˈpī\

Origin of pi

origin unknown


First Known Use: circa 1659


3

pi

verb

Definition of pi

piedpi·ing or pie·ing

  1. transitive verb
  2. :  to spill or throw (type or type matter) into disorder

  3. intransitive verb
  4. :  to become pied



1889

First Known Use of pi

1889

Variants of pi

also pie

4

pi

adjective

Definition of pi

  1. 1 :  not intended to appear in final printing <pi lines>

  2. 2 :  capable of being inserted only by hand <pi characters>



Circa 1940

First Known Use of pi

circa 1940

Variants of pi

also pie

PI

abbreviation

Definition of PI

  1. 1 Philippine Islands

  2. 2 private investigator

  3. 3 programmed instruction





PI Defined for Kids

pi

play
noun \ˈpī\

Definition of pi

plural pis \ˈpīz\

  1. 1 :  the symbol π representing the ratio of the circumference of a circle to its diameter

  2. 2 :  the ratio itself having a value of about 3.1416




Learn More about pi


Seen and Heard

What made you want to look up pi? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

February 9, 2016

marked by high spirits and laughter

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image1037863653

Which of the following refers to thin, bending ice, or to the act of running over such ice?

kittly-benders pince-nez spindrift duvet
Name That Thing

10 quick questions: hear them, spell them, and see how your skills compare to the crowd.

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ