5
inimical(adjective, offensive, negative, foul, unhealthy)
5
malefic(adjective, negative, harmful, threatening, injurious)
5
pestilent(adjective, harmful, dangerous, fatal, poisonous)
5
vicious(adjective, mean, bad, evil, nasty)
4
devastating(adjective, bad, evil, wicked, harmful)
4
disturbing(adjective, harmful, threatening, unfavorable, ominous)
4
foul(offensive, disgusting, unhealthy, harmful, poisonous)
4
malevolent(adjective, mean, bad, wrong, evil)
4
narcotic
4
sinister(adjective, bad, evil, nasty, negative)
4
unfavorable(adjective, harmful, threatening, damaging, ominous)
3
cataclysmic(adjective, harmful, injurious, damaging, deadly)
3
corruptive
3
nasty(adjective, mean, evil, cruel, hateful)
3
pestiferous(adjective, bad, evil, harmful, injurious)
3
unhealthful(adjective, offensive, foul, disgusting, unhealthy)
3
violent
2
pestilential(adjective, bad, evil, harmful, injurious)
2
corroding(injurious, damaging, destructive)
2
corrupting(distressing, harmful, injurious, damaging, destructive)
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APASmart Define. (2016). deleterious thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/deleterious/thesaurus/synonyms
ChicagoSmart Define. 2016. "deleterious thesaurus" https://smartdefine.org/deleterious/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2016, deleterious thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/deleterious/thesaurus/synonyms>.
MLASmart Define. "deleterious thesaurus" 24 March 2016. Web. 24 September 2026. <https://smartdefine.org/deleterious/thesaurus/synonyms>