11
wanton(adjective, mean, cruel, behavior, senseless)
10
hardhearted(adjective, mean, hard, cold, cruel)
10
malevolent(adjective, mean, evil, nasty, harsh)
10
obdurate(adjective, person, mean, hard, tough)
10
spiteful(adjective, person, mean, evil, nasty)
10
stern(adjective, person, appearance, mean, hard)
10
tough(adjective, hard, severe, rough, harsh)
9
dog-eat-dog(adjective, mean, hard, harsh, cruel)
9
fiendish(adjective, nasty, cruel, vicious, wicked)
9
uncompromising(adjective, hard, rough, harsh, cruel)
8
cold(adjective, mean, hard, tough, severe)
8
inflexible(adjective, person, hard, rough, harsh)
8
murderous(adjective, hard, tough, harsh, violent)
8
stony-hearted(adjective, cold, cruel, unfeeling, unsympathetic)
8
unfriendly(adjective, person, evil, negative, unfeeling)
8
unsparing(adjective, mean, severe, rough, difficult)
7
sinister(adjective, person, evil, negative, behavior)
7
bloody(adjective, hard, tough, harsh, violent)
7
inconsiderate(adjective, person, negative, behavior, senseless)
7
malicious(adjective, mean, evil, nasty, harsh)
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APASmart Define. (2016). merciless thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/merciless/thesaurus/synonyms
ChicagoSmart Define. 2016. "merciless thesaurus" https://smartdefine.org/merciless/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2016, merciless thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/merciless/thesaurus/synonyms>.
MLASmart Define. "merciless thesaurus" 31 March 2016. Web. 27 September 2026. <https://smartdefine.org/merciless/thesaurus/synonyms>