4
horrifying(adjective, awful, violent, terrible, shocking)
4
indirect(adjective, rambling, circuitous, tortuous, unintended)
4
infamous(adjective, behavior, vice, aroused negative)
4
inimical(adjective, negative, harmful, injurious, damaging)
4
maleficent
4
odious(adjective, person, tough, offensive, dark)
4
perfidious(adjective, false, corrupt, dishonest, immoral)
4
repulsive(adjective, person, evil, feelings)
4
shadowy(adjective, sorrow, depress, sadness, emotion)
4
shocking(adjective, appearance, offensive, unpleasant, awful)
4
uncanny(adjective, bad, awful, disgusting, sinful)
4
underhand(adjective, false, immoral, deceitful, lying)
4
unpleasant(adjective, person, mean, hard, severe)
4
unprincipled(adjective, false, corrupt, dishonest, immoral)
4
woeful(adjective, evil, nasty, sad, unhappy)
3
Mephistophelian
3
abject(adjective, sad, unhappy, unpleasant, woe)
3
abominable(adjective, evil)
3
apocalyptic(adjective, nasty, menacing)
3
awful(nasty, terrible, dreadful, disturbing, scary)
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APASmart Define. (2016). sinister thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/sinister/thesaurus/synonyms
ChicagoSmart Define. 2016. "sinister thesaurus" https://smartdefine.org/sinister/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2016, sinister thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/sinister/thesaurus/synonyms>.
MLASmart Define. "sinister thesaurus" 3 April 2016. Web. 24 September 2026. <https://smartdefine.org/sinister/thesaurus/synonyms>