The Collaborative International Dictionary of English v.0.48:

Acrid \Ac"rid\, a. [L. acer sharp; prob. assimilated in form to
   acid. See Eager.]
   1. Sharp and harsh, or bitter and not, to the taste; pungent;
      as, acrid salts.
      [1913 Webster]

   2. Causing heat and irritation; corrosive; as, acrid
      secretions.
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   3. Caustic; bitter; bitterly irritating; as, acrid temper,
      mind, writing.
      [1913 Webster]

   Acrid poison, a poison which irritates, corrodes, or burns
      the parts to which it is applied.
      [1913 Webster] Acridity