1. (adverb)erstwhile(a), former(a), old, onetime(a), one-time(a), quondam(a), sometime(a) belonging to some prior time Antonyms: present(a), future
2. (adverb)once, formerly, at one time, erstwhile, erst at a previous time Synonyms: at once, erst, at one time, formerly, erstwhile, at a time, one time, in one case, once Antonyms: future, present(a)
Synonyms and Antonyms of erstwhile 
