1. (adverb)at a time, at once, at one time simultaneously Synonyms: at once, straightaway, like a shot, now, at one time, straight off, formerly, at a time, directly, immediately, right away, instantly, once, erstwhile, erst, forthwith
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
Synonyms and Antonyms of at one time 
