The Collaborative International Dictionary of English v.0.48:

Deplore \De*plore"\, v. t. [imp. & p. p. Deplored; p. pr. &
   vb. n. Deploring.] [L. deplorare; de- + plorare to cry out,
   wail, lament; prob. akin to pluere to rain, and to E. flow:
   cf. F. d['e]plorer. Cf. Flow.]
   1. To feel or to express deep and poignant grief for; to
      bewail; to lament; to mourn; to sorrow over.
      [1913 Webster]

            To find her, or forever to deplore
            Her loss.                             --Milton.
      [1913 Webster]

            As some sad turtle his lost love deplores. --Pope.
      [1913 Webster]

   2. To complain of. [Obs.] --Shak.
      [1913 Webster]

   3. To regard as hopeless; to give up. [Obs.] --Bacon.

   Syn: To Deplore, Mourn, Lament, Bewail, Bemoan.

   Usage: Mourn is the generic term, denoting a state of grief
          or sadness. To lament is to express grief by outcries,
          and denotes an earnest and strong expression of
          sorrow. To deplore marks a deeper and more prolonged
          emotion. To bewail and to bemoan are appropriate only
          to cases of poignant distress, in which the grief
          finds utterance either in wailing or in moans and
          sobs. A man laments his errors, and deplores the ruin
          they have brought on his family; mothers bewail or
          bemoan the loss of their children.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Deplore \De*plore"\, v. i.
   To lament. --Gray.
   [1913 Webster]

WordNet (r) 3.0 (2006):

deplore
    v 1: express strong disapproval of; "We deplore the government's
         treatment of political prisoners"
    2: 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:

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