7
cruel(adjective, mean, nasty, pain, violent)
7
vicious(adjective, mean, bad, evil, nasty)
6
unhealthy(adjective, offensive, foul, disgusting, distressing)
6
corrupt
6
devastating(adjective, bad, evil, wicked, dreadful)
6
disastrous(adjective, bad, wicked, immoral, dreadful)
6
foul(adjective, offensive, corrupt, disgusting, immoral)
5
calamitous(adjective, bad, wicked, immoral, dreadful)
5
insalubrious(adjective, offensive, foul, disgusting, harmful)
5
catastrophic(adjective, dreadful, harmful, injurious, damaging)
5
ill(adjective, rude, vicious, wicked, hostile)
5
malefic(adjective, negative, grave, harmful, threatening)
5
offensive(adjective, bad, hurtful)
5
subtle
4
killing(adjective, bad, hurtful)
4
miasmic(adjective, bad, hurtful)
4
nefarious(adjective, bad, hurtful)
4
negative(adjective, harmful, injurious, unfavorable, hurtful)
4
ominous(adjective, cruel, unkind, upsetting, threatening)
4
unfavorable(adjective, contrary, dreadful, harmful, threatening)
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APASmart Define. (2016). pernicious thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/pernicious/thesaurus/synonyms
ChicagoSmart Define. 2016. "pernicious thesaurus" https://smartdefine.org/pernicious/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2016, pernicious thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/pernicious/thesaurus/synonyms>.
MLASmart Define. "pernicious thesaurus" 24 March 2016. Web. 24 September 2026. <https://smartdefine.org/pernicious/thesaurus/synonyms>