The Collaborative International Dictionary of English v.0.48:

Bemoan \Be*moan"\, v. t. [imp. & p. p. Bemoaned; p. pr. & vb.
   n. Bemoaning.] [OE. bimenen, AS. bem?nan; pref. be- + m?nan
   to moan. See Moan.]
   To express deep grief for by moaning; to express sorrow for;
   to lament; to bewail; to pity or sympathize with.
   [1913 Webster]

         Implores their pity, and his pain bemoans. --Dryden.
   [1913 Webster]

   Syn: See Deplore.
        [1913 Webster]

WordNet (r) 3.0 (2006):

bemoan
    v 1: regret strongly; "I deplore this hostile action"; "we
         lamented the loss of benefits" [syn: deplore, lament,
         bewail, bemoan]

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "bemoan":
   be sorry for, bewail, complain, deplore, dirge, elegize,
   give sorrow words, grieve, grieve for, keen, knell, lament, moan,
   mourn, regret, repine, rue, rue the day, sigh, sing the blues,
   sorrow, weep, weep for, weep over