was (past of is), Middle Gaelic fa ( Dean of Lismore), Irish fa, fa h- (Keat.), Middle Irish fa h-, Early Irish ba h-, *bât, *(e)bhu-â-t; Latin -bat, -bamus, of refe-bam, etc.; root bheu, to be. See bu, the form now used.
Etymological dictionary of the Gaelic language.
Alexander Gairm Publications.
1982.