Middle English formest, from Old English fyrmest, formest "earliest, first, most prominent," from Proto-Germanic *furmista-/*frumista- (related to Old English fruma "beginning"), from PIE *pre-mo-, suffixed (superlative) form of root *per- (1) "forward," hence "through, in front of, before, first" + additional superlative suffix -est. For the -m-, see -most, and compare similarly formed Old Frisian formest, Gothic frumists. Altered on the assumption that it is a compound of fore and most. The same compound without the superlative -m- is first. Also in Old English as an adverb, "first of all, at first, in the first place."