40
poisonous(adjective, help, heavy, foul, unhealthy)
35
deadly(adjective, bad, evil, unhealthy, harmful)
30
harmful(adjective, dangerous, injurious, damaging, deadly)
25
noxious(adjective, unhealthy, harmful, dangerous, injurious)
20
venomous(adjective, help, bad, evil, hateful)
19
virulent(adjective, help, unhealthy, harmful, noxious)
19
baneful(adjective, bad, offensive, foul, unhealthy)
19
deleterious(adjective, bad, evil, offensive, foul)
18
lethal(adjective, bad, evil, harmful, dangerous)
18
pernicious(adjective, bad, evil, offensive, foul)
17
destructive(adjective, unhealthy, harmful, dangerous, injurious)
14
fatal(adjective, bad, evil, harmful, dangerous)
14
dangerous(adjective, harmful, injurious, damaging, fatal)
12
detrimental(adjective, bad, evil, offensive, foul)
11
injurious(adjective, bad, harmful, dangerous, damaging)
10
baleful(adjective, bad, evil, harmful, injurious)
10
malignant(adjective, offensive, foul, unhealthy, dangerous)
10
toxicant(adjective, help, poisonous)
9
septic(adjective, unhealthy, unclean, poisonous, insalubrity)
8
mephitic(adjective, help, poisonous, insalubrity)
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APASmart Define. (2015). toxic thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/toxic/thesaurus/synonyms
ChicagoSmart Define. 2015. "toxic thesaurus" https://smartdefine.org/toxic/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2015, toxic thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/toxic/thesaurus/synonyms>.
MLASmart Define. "toxic thesaurus" 17 July 2015. Web. 20 September 2026. <https://smartdefine.org/toxic/thesaurus/synonyms>