The Collaborative International Dictionary of English v.0.48:

Exasperate \Ex*as"per*ate\, v. t. [imp. & p. p. Exsasperated;
   p. pr. & vb. n. Exasperating.]
   1. To irritate in a high degree; to provoke; to enrage; to
      excite or to inflame the anger of; as, to exasperate a
      person or his feelings.
      [1913 Webster]

            To exsasperate them against the king of France.
                                                  --Addison.
      [1913 Webster]

   2. To make grievous, or more grievous or malignant; to
      aggravate; to imbitter; as, to exasperate enmity.
      [1913 Webster]

            To exasperate the ways of death.      --Sir T.
                                                  Browne.

   Syn: To irritate; provoke. See Irritate.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Exasperate \Ex*as"per*ate\, a. [L. exasperatus, p. p. of
   exsasperare to roughen, exasperate; ex out (intens.) +
   asperare to make rough, asper rough. See Asperity.]
   Exasperated; imbittered. [Obs.] --Shak.
   [1913 Webster]

         Like swallows which the exasperate dying year
         Sets spinning.                           --Mrs.
                                                  Browning.
   [1913 Webster]

WordNet (r) 3.0 (2006):

exasperate
    v 1: exasperate or irritate [syn: exacerbate, exasperate,
         aggravate]
    2: make furious [syn: infuriate, exasperate, incense]
    3: make worse; "This drug aggravates the pain" [syn: worsen,
       aggravate, exacerbate, exasperate] [ant: ameliorate,
       amend, better, improve, meliorate]