9
wicked(adjective, bad, corrupt, negative, immoral)
8
grievous(adjective, severe, painful)
8
hostile(adjective, person, mean, bad, wrong)
8
not good
8
risky(adjective, severe, rude, awful, terrible)
8
unsafe(adjective, risky, dangerous, injurious, damaging)
8
venomous(adjective, bad, evil, dangerous, injurious)
7
pestiferous(adjective, bad, injurious, damaging, deadly)
7
suicidal(adjective, violent, cruel, injurious, damaging)
7
unfavourable
6
cataclysmic(adjective, dreadful, unfortunate, injurious, damaging)
6
distressing(adjective, awful, terrible, cruel, unkind)
6
disturbing(adjective, awful, terrible, dreadful, unfavorable)
6
hazardous(adjective, risky, dangerous, injurious, unsafe)
6
inauspicious
6
malefic(adjective, negative, threatening, injurious, damaging)
6
menacing(adjective, risky, threatening, dangerous, injurious)
6
unfavorable(adjective, contrary, dreadful, threatening, unfortunate)
6
unhealthful(adjective, offensive, foul, disgusting, injurious)
6
untoward
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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>