The Collaborative International Dictionary of English v.0.48:

Poison \Poi"son\, v. t. [imp. & p. p. Poisoned; p. pr. & vb.
   n. Poisoning.] [Cf. OF. poisonner, F. empoissoner, L.
   potionare to give to drink. See Poison, n.]
   [1913 Webster]
   1. To put poison upon or into; to infect with poison; as, to
      poison an arrow; to poison food or drink. "The ingredients
      of our poisoned chalice." --Shak.
      [1913 Webster]

   2. To injure or kill by poison; to administer poison to.
      [1913 Webster]

            If you poison us, do we not die ?     --Shak.
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   3. To taint; to corrupt; to vitiate; as, vice poisons
      happiness; slander poisoned his mind.
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            Whispering tongues can poison truth.  --Coleridge.
      [1913 Webster]

WordNet (r) 3.0 (2006):

poisoning
    n 1: the physiological state produced by a poison or other toxic
         substance [syn: poisoning, toxic condition,
         intoxication]
    2: the act of giving poison to a person or animal with the
       intent to kill