The comparative of OE 'forma' (first), from PIE *per- (forward) — sibling of 'first' (the superlative), both meaning 'more before.'
Having previously been; of an earlier time; the first of two things mentioned.
From Middle English "former," a comparative form of "forme" ("first, earliest"), from Old English "forma" ("first, foremost"), the superlative of "fore" ("before"), from Proto-Germanic *furmô ("first"), from PIE *pr̥H-mo- ("foremost"), a superlative of *per- ("forward, through"). The PIE root *per- is among the most productive in the language: it yielded Latin "prīmus" ("first," whence "prime," "primary," "primitive"), Greek "πρῶτος" (prôtos, "first," whence "prototype," "protocol"), Sanskrit "pūrva-" ("former, earlier"), Old English "fore" ("before"), "first" (another superlative of the same root), "far," "for," "forth," and "from." The formation of "former" is unusual: it adds a comparative suffix -er to what