Definition of poisonous adjective from the Oxford Advanced American Dictionary

      

    poisonous

     adjective
    adjective
    NAmE//ˈpɔɪzənəs//
     
     
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  1. 1causing death or illness if swallowed or absorbed into the body synonym toxic poisonous chemicals/plants This gas is highly poisonous. The leaves of certain trees are poisonous to cattle.
  2. 2(of animals and insects) producing a poison that can cause death or illness if the animal or insect bites you synonym venomous poisonous snakes a tiny spider with a poisonous bite
  3. 3extremely unpleasant or unfriendly a poisonous person the poisonous atmosphere in the office
See the Oxford Advanced Learner's Dictionary entry: poisonous