Number & MeasureGreek → English
Pi
/paɪ/noun
The ratio of a circle's circumference to its diameter, roughly 3.14159.
The Greek roots
πῖ
pî
the letter p
Literally: “the letter p”
Follow a root:πῖ1 word
The story of the word
The letter itself came from Phoenician with the rest of the alphabet and means nothing on its own. Its mathematical career began in 1706, when William Jones used π for the circle ratio, picking the first letter of περιφέρεια, the periphery. Euler adopted the notation in the 1730s, and after Euler nobody else had a vote.
- How it travelled
- Ancient Greek → mathematical notation → English
- First recorded
- 18th century
Same family
pionperimeterperiphery
In a sentence
She can recite pi to forty places and cannot remember her own phone number.