18
quickly(adverb, rapidly, pronto)
17
perpetual(adjective, strain, firmness, labour, hardiness)
17
robust(adjective, strain, firmness, labour, hardiness)
17
speedily(adverb, quickly, rapidly, pronto)
17
sturdily(adjective, adverb, strain, firmness, labour)
16
secure(verb, adjective, calm, strong, free)
16
set(adjective, calm, strong, secure, tough)
16
proof(noun, adjective, strain, firmness, labour)
16
resilient(adjective, strain, firmness, labour, hardiness)
16
rock-solid(adjective, strain, firmness, labour, hardiness)
16
immune(adjective, strain, firmness, safe, labour)
16
long-standing(adjective, strain, firmness, labour, hardiness)
16
rapidly(adverb, quickly, pronto)
15
debauched(adjective, open, light, evil, wild)
15
impregnable(adjective, strain, firm, firmness, constant)
15
flying(adjective, keen, energetic, active, speedy)
15
profligate(adjective, open, light, free, evil)
15
prompt(adjective, adverb, activity, direct, keen)
15
swiftly(adverb, quickly, rapidly, pronto)
14
diet(noun, verb, reduce, slim, refrain)
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APASmart Define. (2016). fast thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/fast/thesaurus/synonyms
ChicagoSmart Define. 2016. "fast thesaurus" https://smartdefine.org/fast/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2016, fast thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/fast/thesaurus/synonyms>.
MLASmart Define. "fast thesaurus" 1 April 2016. Web. 22 September 2026. <https://smartdefine.org/fast/thesaurus/synonyms>