The Collaborative International Dictionary of English v.0.48:

deprecatory \dep"re*ca*to*ry\ (d[e^]p"r[-e]*k[.a]*t[-o]*r[y^]),
   a. [L. deprecatorius.]
   1. Tending to remove or avert evil by prayer; apologetic.
      [1913 Webster]

            Humble and deprecatory letters.       --Bacon.
      [1913 Webster]

   2. Serving to deprecate; expressing a low opinion of.

   Syn: belittling, disparaging, depreciative, deprecatory,
        depreciatory, derogatory, detractive, detracting,
        slighting, pejorative, denigratory.
        [PJC]

WordNet (r) 3.0 (2006):

deprecatory
    adj 1: tending to diminish or disparage; "belittling comments";
           "managed a deprecating smile at the compliment";
           "deprecatory remarks about the book"; "a slighting
           remark" [syn: belittling, deprecating, deprecative,
           deprecatory, depreciative, depreciatory,
           slighting]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "deprecatory":
   abusive, back-biting, belittling, bitchy, blackening, blameful,
   calumniatory, calumnious, catty, censorious, condemnatory,
   contemptuous, contumelious, damnatory, defamatory, denunciatory,
   deprecative, depreciative, depreciatory, derisive, derisory,
   derogative, derogatory, detractory, diffident, disparaging,
   execrating, execrative, execratory, invective, inveighing,
   judgmental, libelous, minimizing, objurgatory, pejorative,
   priggish, reproachful, reprobative, reviling, ridiculing,
   scandalous, scoffing, scurrile, scurrilous, self-deprecating,
   self-depreciating, self-depreciative, self-distrustful,
   self-doubting, self-effacing, slanderous, slighting,
   unselfconfident, unselfreliant, vilifying, vituperative