16
unwholesome(adjective, offensive, unpleasant, foul, disgusting)
15
inimical(adjective, person, unfriendly, antagonistic, contrary)
15
poisonous(adjective, bad, evil, offensive, cruel)
14
malign(adjective, injurious, hurtful)
14
deadly(adjective, bad, evil, cruel, unkind)
14
mischievous(adjective, help, offensive, negative, foul)
13
prejudicial(adjective, bad, cruel, negative, hurtful)
12
catastrophic(adjective, dreadful, unfortunate, injurious, damaging)
12
fatal(adjective, bad, evil, dreadful, dangerous)
12
virulent(adjective, unhealthy, injurious, hurtful, noxious)
11
ill(adjective, help, mean, bad, evil)
11
lethal(adjective, bad, evil, risky, dangerous)
10
malicious(adjective, bad, cruel, corrupt, injurious)
10
nocuous(adjective, cruel, negative, unkind, dangerous)
10
painful(adjective, bad, severe, offensive, awful)
9
nasty(adjective, person, bad, evil, offensive)
9
calamitous(adjective, severe, awful, terrible, wicked)
9
insalubrious(adjective, offensive, unpleasant, foul, disgusting)
9
noisome(adjective, bad, evil, offensive, foul)
9
sinister(adjective, bad, evil, nasty, injurious)
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APASmart Define. (2016). harmful thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/harmful/thesaurus/synonyms
ChicagoSmart Define. 2016. "harmful thesaurus" https://smartdefine.org/harmful/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2016, harmful thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/harmful/thesaurus/synonyms>.
MLASmart Define. "harmful thesaurus" 24 March 2016. Web. 22 September 2026. <https://smartdefine.org/harmful/thesaurus/synonyms>