29
immediately(noun, adverb, interjection, time, freely)
27
without delay(noun, expression, idiom, adverb, directly)
22
directly(noun, adverb, time, first, immediately)
22
instantly(noun, adverb, time, first, now)
21
right away(noun, verb, expression, adverb, phrasal verb)
19
promptly(noun, adverb, first, now, directly)
18
pronto(adverb, now, directly, immediately, quickly)
15
straight away(noun, verb, adverb, phrasal verb, directly)
14
quickly(adverb, interjection, sharp, straight, dead)
13
forthwith(adverb, time, now, directly, immediately)
13
straightaway(adverb, time, dead, first, now)
12
instantaneously(adverb, first, directly, immediately, quickly)
12
now(adverb, time, prompt, directly, immediately)
12
speedily(adverb, straight, directly, immediately, quickly)
10
as soon as(adverb, time, immediately, soon)
10
swiftly(adverb, directly, immediately, quickly, rapidly)
9
straight off(verb, expression, adverb, phrasal verb, time)
7
in no time(noun, expression, idiom, first, directly)
7
instanter(adverb, now, directly, immediately, quickly)
6
rapidly(adverb, directly, immediately, quickly, instantly)
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APASmart Define. (2015). at once thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/at_once/thesaurus/synonyms
ChicagoSmart Define. 2015. "at once thesaurus" https://smartdefine.org/at_once/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, at once thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/at_once/thesaurus/synonyms>.
MLASmart Define. "at once thesaurus" 14 April 2015. Web. 22 September 2026. <https://smartdefine.org/at_once/thesaurus/synonyms>