7
at times(expression, idiom, adverb, time, moment)
7
in the past(verb, expression, idiom, adverb, phrasal verb)
7
occasionally(expression, adverb, time, moment, period)
6
on one occasion(expression, adjective, idiom, adverb, past)
6
onetime(adjective, last, original, past, primitive)
6
past(adjective, original, old, previous, obsolete)
6
whilom(adjective, adverb, past, precede)
5
after(adverb, conjunction, immediately, when)
5
bygone(adjective, adverb, last, original, late)
5
ever(adverb, conjunction)
5
hitherto(adverb, the past)
5
time
5
time was(expression, adjective, adverb, late, old)
4
back(adjective, adverb, late, past, earlier)
4
erst
4
now and again(expression, idiom, time, moment, rare)
4
on occasion(expression, adverb, time, moment, period)
4
one(adjective, adverb, past, then, previously)
4
previous(adjective, adverb, last, late, old)
4
some time ago(expression, idiom, adverb, late, earlier)
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APASmart Define. (2016). once thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/once/thesaurus/synonyms
ChicagoSmart Define. 2016. "once thesaurus" https://smartdefine.org/once/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2016, once thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/once/thesaurus/synonyms>.
MLASmart Define. "once thesaurus" 30 March 2016. Web. 21 September 2026. <https://smartdefine.org/once/thesaurus/synonyms>