5
detrimental(adjective, bad, evil, negative, harmful)
5
fearful(adjective, awful, terrible, dreadful, weird)
5
fearsome(adjective, bad, awful, disgusting, black)
5
felonious(adjective, wicked, vice)
5
flagitious(adjective, vice)
5
frightening(adjective, person, hard, severe, dark)
5
frigid(adjective, person, unwarmhearted)
5
ghastly(adjective, bad, awful, disgusting, sinful)
5
glacial(adjective, person, unwarmhearted)
5
grave(adjective, unpleasant, sorrow, depress, sadness)
5
half-spirited(adjective, person, unwarmhearted)
5
hardhearted(adjective, person, unwarmhearted)
5
horrendous(adjective, bad, awful, disgusting, sinful)
5
horrible(adjective, obscure, nasty, dark, unpleasant)
5
horrid(appearance, terrible, shocking, explicit, hopeless)
5
icy(adjective, person, unwarmhearted)
5
immoral(adjective, wicked)
5
improper(adjective, corrupt, wicked, unreasonable, dishonest)
5
miserable(adjective, sad, unhappy, unpleasant, woe)
5
monstrous(adjective, evil, awful, terrible, dreadful)
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APASmart Define. (2016). sinister thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/sinister/thesaurus/synonyms
ChicagoSmart Define. 2016. "sinister thesaurus" https://smartdefine.org/sinister/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2016, sinister thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/sinister/thesaurus/synonyms>.
MLASmart Define. "sinister thesaurus" 3 April 2016. Web. 22 September 2026. <https://smartdefine.org/sinister/thesaurus/synonyms>