14
noxious(adjective, help, bad, evil, foul)
13
pestiferous(adjective, bad, evil, harmful, injurious)
12
deadly(adjective, help, bad, evil, harmful)
12
baneful(adjective, help, bad, evil, harmful)
11
harmful(adjective, injurious, damaging, deadly, destructive)
11
pernicious(adjective, help, bad, evil, harmful)
9
pestilent(adjective, help, unhealthy, dangerous, deadly)
9
fatal(adjective, bad, evil, harmful, injurious)
9
toxic(adjective, bad, evil, harmful, injurious)
8
lethal(adjective, bad, evil, harmful, injurious)
8
poisonous(adjective, bad, foul, harmful, injurious)
7
malignant(adjective, help, unhealthy, deadly, diseased)
6
detrimental(adjective, bad, evil, harmful, injurious)
6
dangerous(offensive, foul, disgusting, fatal, noxious)
6
destructive(adjective, unhealthy, harmful, injurious, poisonous)
6
epidemic(noun, infectious)
6
troublesome(adjective, harmful, bothersome, worrisome)
5
deleterious(adjective, bad, evil, harmful, injurious)
5
infectious(adjective, catching, spreading)
5
noisome(adjective, bad, evil, offensive, foul)
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APASmart Define. (2015). pestilential thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/pestilential/thesaurus/synonyms
ChicagoSmart Define. 2015. "pestilential thesaurus" https://smartdefine.org/pestilential/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2015, pestilential thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/pestilential/thesaurus/synonyms>.
MLASmart Define. "pestilential thesaurus" 14 April 2015. Web. 21 September 2026. <https://smartdefine.org/pestilential/thesaurus/synonyms>