13
fatal(adjective, dangerous, deadly, diseased, lethal)
12
detrimental(adjective, mean, bad, evil, nasty)
12
noxious(adjective, help, mean, bad, evil)
11
baneful(adjective, help, offensive, foul, harmful)
11
deleterious(adjective, mean, bad, evil, nasty)
11
sinister(adjective, bad, evil, nasty, negative)
10
injurious(adjective, mean, bad, evil, nasty)
10
bad(adjective, mean, evil, nasty, corrupt)
10
dangerous(adjective, bad, heavy, treacherous, unsafe)
10
lethal(adjective, dangerous, deadly, diseased)
9
cancerous(adjective, diseased, spreading)
9
disadvantageous(adjective, injurious, damaging, destructive, inexpedience)
9
hostile(adjective, mean, nasty, cold, negative)
9
mean(adjective, animal, nasty, attitude, cruel)
9
mischievous(adjective, mean, evil, nasty, wicked)
9
toxic(adjective, offensive, foul, unhealthy, dangerous)
8
mortal(adjective, dangerous, deadly, diseased)
7
antagonistic(adjective, mean, nasty, cold, negative)
7
damaging(adjective, bad, negative, vile, hateful)
7
pestilential(adjective, help, unhealthy, deadly, diseased)
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APASmart Define. (2016). malignant thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/malignant/thesaurus/synonyms
ChicagoSmart Define. 2016. "malignant thesaurus" https://smartdefine.org/malignant/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2016, malignant thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/malignant/thesaurus/synonyms>.
MLASmart Define. "malignant thesaurus" 24 March 2016. Web. 21 September 2026. <https://smartdefine.org/malignant/thesaurus/synonyms>