14
baneful(adjective, help, unhealthy, dangerous, injurious)
14
deadly(adjective, help, unhealthy, harmful, dangerous)
10
noxious(adjective, help, unhealthy, dangerous, injurious)
10
pernicious(adjective, help, bad, unhealthy, dangerous)
10
fatal(adjective, dangerous, deadly, lethal)
10
pestiferous(adjective, harmful, dangerous, fatal, poisonous)
10
pestilential(adjective, help, unhealthy, dangerous, deadly)
8
poisonous(adjective, unhealthy, harmful, deadly, fatal)
8
malignant(adjective, help, unhealthy, lethal)
7
lethal(adjective, harmful, dangerous, deadly, fatal)
7
deathly(adjective, lethal)
7
harmful(adjective, unhealthy, dangerous, fatal, unwholesome)
7
mortal(adjective, dangerous, deadly, lethal)
7
unhealthy(adjective, unhealthy, harmful, diseased, unwholesome)
7
virulent(adjective, help, unhealthy, deadly, fatal)
4
infectious(adjective, dangerous, catching, spreading, transferable)
4
bothersome
4
deleterious(adjective, harmful, dangerous, fatal, poisonous)
4
galling
4
hurtful(adjective, harmful, poisonous, toxic)
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APASmart Define. (2015). pestilent thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/pestilent/thesaurus/synonyms
ChicagoSmart Define. 2015. "pestilent thesaurus" https://smartdefine.org/pestilent/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, pestilent thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/pestilent/thesaurus/synonyms>.
MLASmart Define. "pestilent thesaurus" 14 April 2015. Web. 22 September 2026. <https://smartdefine.org/pestilent/thesaurus/synonyms>