The Collaborative International Dictionary of English v.0.48:

Agony \Ag"o*ny\, n.; pl. Agonies. [L. agonia, Gr. ?, orig. a
   contest, fr. ?: cf. F. agonie. See Agon.]
   1. Violent contest or striving.
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            The world is convulsed by the agonies of great
            nations.                              --Macaulay.
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   2. Pain so extreme as to cause writhing or contortions of the
      body, similar to those made in the athletic contests in
      Greece; and hence, extreme pain of mind or body; anguish;
      paroxysm of grief; specifically, the sufferings of Christ
      in the garden of Gethsemane.
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            Being in an agony he prayed more earnestly. --Luke
                                                  xxii. 44.
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   3. Paroxysm of joy; keen emotion.
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            With cries and agonies of wild delight. --Pope.
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   4. The last struggle of life; death struggle.
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   Syn: Anguish; torment; throe; distress; pangs; suffering.

   Usage: Agony, Anguish, Pang. These words agree in
          expressing extreme pain of body or mind. Agony denotes
          acute and permanent pain, usually of the whole
          system., and often producing contortions. Anguish
          denotes severe pressure, and, considered as bodily
          suffering, is more commonly local (as anguish of a
          wound), thus differing from agony. A pang is a
          paroxysm of excruciating pain. It is severe and
          transient. The agonies or pangs of remorse; the
          anguish of a wounded conscience. "Oh, sharp convulsive
          pangs of agonizing pride!" --Dryden.
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