The Collaborative International Dictionary of English v.0.48:

Commiserate \Com*mis"er*ate\, v. t. [imp. & p. p.
   Commiserated; p. pr. & vb. n. Commiserating.] [L.
   commiseratus, p. p. of commiserari to commiserate; com- +
   miserari to pity. See Miserable.]
   To feel sorrow, pain, or regret for; to pity.
   [1913 Webster]

         Then must we those, who groan, beneath the weight
         Of age, disease, or want, commiserate.   --Denham.
   [1913 Webster]

         We should commiserate our mutual ignorance. --Locke.

   Syn: To pity; compassionate; lament; condole.
        [1913 Webster]

WordNet (r) 3.0 (2006):

commiserate
    v 1: to feel or express sympathy or compassion [syn:
         commiserate, sympathize, sympathise]