Longman Dictionary of Contemporary English homepage

Date: 1800-1900
Origin: From the name of the first letter of Greek periphereia 'distance around a circle'

pi

noun
     
Related topics: Maths, Numbers
pi [uncountable]
technicalHM a number that is represented by the Greek letter (π) and is equal to the distance around a circle, divided by its width

Dictionary pictures of the day
Do you know what each of these is called?
What is the word for picture 1? What is the word for picture 2? What is the word for picture 3? What is the word for picture 4?
Click on any of the pictures above to find out what it is called.

Explore our topic dictionary