7
vicious(adjective, nasty, unpleasant, negative, wicked)
7
cat-hearted(adjective, person, behavior, unwarmhearted, aroused negative)
7
cold(adjective, person, unwarmhearted)
7
devilish(adjective, evil)
7
dreary(adjective, obscure, sad, dark, sorrow)
7
gruesome(adjective, bad, awful, disgusting, sinful)
7
ill(adjective, bad, evil)
7
infernal
7
macabre(adjective, bad, awful, disgusting, black)
7
misaffectionate(adjective, person, negative, unwarmhearted)
7
misanthropic(adjective, person, negative, unwarmhearted)
7
nefarious(adjective, evil, vice)
7
obnoxious(adjective, evil, rough, nasty, dark)
7
treacherous(adjective, rough, nasty, dark, unpleasant)
7
unpromising(adjective, warning, threatening, unfavorable, desperate)
6
bleak(adjective, appearance, obscure, sad, dark)
6
diabolical(adjective, evil)
6
disconsolate(adjective, sad, unhappy, unpleasant, sorrow)
6
foul(adjective, evil, malevolent, vice)
6
glowering(adjective, person, tough, offensive, dark)
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APASmart Define. (2016). sinister thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/sinister/thesaurus/synonyms
ChicagoSmart Define. 2016. "sinister thesaurus" https://smartdefine.org/sinister/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, sinister thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/sinister/thesaurus/synonyms>.
MLASmart Define. "sinister thesaurus" 3 April 2016. Web. 23 September 2026. <https://smartdefine.org/sinister/thesaurus/synonyms>