Pi
来自Big Physics
Greek.
wiktionary
From Ancient Greek πεῖ(peî). 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.
Abbreviations
etymonline
pi (n.)
Greek letter corresponding to the Roman P, from Phoenician, literally "little mouth." As the name of the mathematical constant for the ratio of the circumference of a circle to the diameter, from 1841 in English, used in Latin 1748 by Swiss mathematician Leonhard Euler (1707-1783), as an abbreviation of Greek periphereia "periphery." For the printer's term for mixed type (often spelled pi), see pie (3).
