Added 10 October 2026
pi
/paɪ/ noun
noun Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about pi at Wordnik → Where our words come from →
- The ratio of the circumference to the diameter of a circle; approximately equal to 3.14159265358979323846...
- Someone who can be employed as a detective to collect information.
- The scientist in charge of an experiment or research project.
Origin
From Koine Greek πῖ (pî), from Ancient Greek πεῖ (peî), ultimately from Proto-Semitic *pay- (“mouth”). Doublet of pe. Its mathematical use apparently stems from its use as the first letter in περιφέρεια (periphéreia, “periphery; circumference”) and was first cited in 1706 in the Synopsis Palmariorum Matheseos by William Jones.
From Wiktionary, via Kaikki.org (CC BY-SA)