PSI


Meaning of PSI in English

n.

Pronunciation: ' s ī , ' ps ī

Function: noun

Etymology: Middle English, from Medieval Latin, from Late Greek, from Greek psei

Date: 15th century

: the 23d letter of the Greek alphabet ― see ALPHABET table

Merriam Webster Collegiate English Dictionary.      Merriam Webster - Энциклопедический словарь английского языка.