Any agent which, when introduced into the animal organism, is capable of producing a morbid, noxious, or deadly effect upon it; as, morphine is a deadly poison; the poison of pestilential diseases.(noun)
source: webster1913
verb (v)
spoil as if by poison(verb.social)
Example: Poison someone's mind.
Poison the atmosphere in the office.
source: wordnet30
kill with poison(verb.contact)
Example: She poisoned her husband.
source: wordnet30
add poison to(verb.change)
Example: Her husband poisoned her drink in order to kill her.