From poison +‎ -ous.


  • IPA(key): /ˈpɔɪzənəs/, /ˈpɔɪznəs/
  • (file)


poisonous (comparative more poisonous, superlative most poisonous)

  1. Containing sufficient poison to be dangerous to touch or ingest.
    • 2003, Charles L. Fergus, Common Edible and Poisonous Mushrooms of the Northeast, Stackpole Books (→ISBN), page 77:
      I had picked a mushroom so poisonous that particles of it, stuck to my fingers and accidentally swallowed, could have made me deathly ill, and a piece the size of my thumb could have killed me.
    Synonyms: poisoned, toxic, venomous, attery (dialectal or archaic)
    Antonyms: nonpoisonous, unpoisonous
  2. (figurative) Negative, harmful.
    • 2013, Kylie Griffin, Allegiance Sworn, Penguin (→ISBN)
      He didn't want to end up like his grandfather, bitter and intractable, consumed in his hatred like an addict on haze — a poisonous attitude that would possess him all his remaining years.
    Synonym: toxic

Usage notesEdit

Some speakers make a distinction between poisonous (releasing toxins when eaten), and venomous (releasing toxins (known as venom in this case) by biting a target), especially in non-colloquial speech.

Derived termsEdit