|Definition - Another name for the pluperfect, an aspect that conveys the idea that a past event has been completed prior to another past event, e.g. I had finished my letter before he arrived.|
Oxford English Dictionary - The term's first citation is from 1530:
"The thre generall distinctions of tyme, present, parfytly past, and to come."
(Jehan Palsgrave, Lesclarcissement de la langue françoyse, Introduction, 32)