Plural of former: people or things that form something, or people who previously held a position or status.
From 'former,' which has two origins: (1) 'one who forms' from Latin 'formare,' or (2) 'previous' from Old English 'forma' (first). The plural simply adds 's.'
The word 'former' is beautifully ambiguous in English—'former students' and 'metal formers' use the same word but mean completely different things, showing how context is everything in language.
Complete word intelligence in one call. Free tier — 50 lookups/day.