adjective
- former; of times past: erstwhile friends.
adverb
- Archaic. formerly; erst.
adjective
- former; one-timemy erstwhile companions
adverb
- archaic long ago; formerly
1560s, from Middle English erest “soonest, earliest,” from Old English ærest, superlative of ær (see ere) + while. As an adjective from 1903. Cognate with Old Saxon and Old High German erist, German erst.