1
hard-line(adjective, strong, hard, tough, severe)
1
hardhearted(adjective, mean, hard, severe, harsh)
1
hatchet job(expression, adjective, mean, severe, harsh)
1
hateful(adjective, animal, mean, evil, nasty)
1
having a killer instinct(expression, adjective, idiom, mean, severe)
1
hearty(adjective, resolute)
1
heavy(adjective, strong, hard, tough, harsh)
1
hellish(adjective, evil, nasty, harsh, vicious)
1
icy
1
immitigable
1
impenitent(adjective, hard, tough, harsh, cruel)
1
implacability
1
impliable
1
inelastic
1
inexpiable
1
insensible(adjective, mean, strong, hard, tough)
1
intent(adjective, resolute)
1
intolerant(adjective, hard, tough, harsh, cruel)
1
iron-fisted(adjective, mean, severe, harsh, cruel)
1
ironfisted(adjective, mean, harsh, cruel, vicious)
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APASmart Define. (2016). implacable thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/implacable/thesaurus/synonyms
ChicagoSmart Define. 2016. "implacable thesaurus" https://smartdefine.org/implacable/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2016, implacable thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/implacable/thesaurus/synonyms>.
MLASmart Define. "implacable thesaurus" 24 March 2016. Web. 21 September 2026. <https://smartdefine.org/implacable/thesaurus/synonyms>