20
former(noun, adjective, adverb, order, time)
18
quondam(adjective, last, original, dead, late)
16
previous(adjective, adverb, last, dead, late)
15
old(adjective, last, late, past, previous)
15
past(adjective, original, old, previous, former)
14
sometime(adjective, adverb, last, original, dead)
13
late(adjective, last, original, dead, old)
12
once(adjective, adverb, last, original, late)
12
prior(adjective, late, old, past, previous)
11
one-time(adjective, last, dead, late, old)
10
before(adverb, head, late, past, previous)
10
whilom(adjective, precede)
9
already(adverb, late, earlier, then, precede)
9
bygone(adjective, last, original, late, old)
9
formerly(adverb, earlier, precede)
9
heretofore(adverb, head, late, past, previous)
9
onetime(adjective, last, original, primitive, venerable)
9
preceding(adjective, late, old, past, previous)
9
previously(adverb, earlier, precede)
8
earlier(adjective, adverb, late, old, past)
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APASmart Define. (2015). erstwhile thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/erstwhile/thesaurus/synonyms
ChicagoSmart Define. 2015. "erstwhile thesaurus" https://smartdefine.org/erstwhile/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2015, erstwhile thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/erstwhile/thesaurus/synonyms>.
MLASmart Define. "erstwhile thesaurus" 14 April 2015. Web. 20 September 2026. <https://smartdefine.org/erstwhile/thesaurus/synonyms>