The Collaborative International Dictionary of English v.0.48:

Anguish \An"guish\, n. [OE. anguishe, anguise, angoise, F.
   angoisse, fr. L. angustia narrowness, difficulty, distress,
   fr. angustus narrow, difficult, fr. angere to press together.
   See Anger.]
   Extreme pain, either of body or mind; excruciating distress.
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         But they hearkened not unto Moses for anguish of
         spirit, and for cruel bondage.           --Ex. vi. 9.
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         Anguish as of her that bringeth forth her first child.
                                                  --Jer. iv. 31.
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   Note: Rarely used in the plural:

               Ye miserable people, you must go to God in
               anguishes, and make your prayer to him.
                                                  --Latimer.
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   Syn: Agony; pang; torture; torment. See Agony.
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The Collaborative International Dictionary of English v.0.48:

Anguish \An"guish\, v. t. [Cf. F. angoisser, fr. L. angustiare.]
   To distress with extreme pain or grief. [R.] --Temple.
   [1913 Webster]

WordNet (r) 3.0 (2006):

anguish
    n 1: extreme mental distress [syn: anguish, torment,
         torture]
    2: extreme distress of body or mind
    v 1: suffer great pains or distress
    2: cause emotional anguish or make miserable; "It pains me to
       see my children not being taught well in school" [syn:
       pain, anguish, hurt]