The Collaborative International Dictionary of English v.0.48:

Demean \De*mean"\, v. t. [imp. & p. p. Demeaned; p. pr. & vb.
   n. Demeaning.] [OF. demener to conduct, guide, manage, F.
   se d['e]mener to struggle; pref. d['e]- (L. de) + mener to
   lead, drive, carry on, conduct, fr. L. minare to drive
   animals by threatening cries, fr. minari to threaten. See
   Menace.]
   1. To manage; to conduct; to treat.
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            [Our] clergy have with violence demeaned the matter.
                                                  --Milton.
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   2. To conduct; to behave; to comport; -- followed by the
      reflexive pronoun.
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            They have demeaned themselves
            Like men born to renown by life or death. --Shak.
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            They answered . . . that they should demean
            themselves according to their instructions.
                                                  --Clarendon.
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   3. To debase; to lower; to degrade; -- followed by the
      reflexive pronoun.
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            Her son would demean himself by a marriage with an
            artist's daughter.                    --Thackeray.
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   Note: This sense is probably due to a false etymology which
         regarded the word as connected with the adjective mean.
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WordNet (r) 3.0 (2006):

demeaning
    adj 1: causing awareness of your shortcomings; "golf is a
           humbling game" [syn: demeaning, humbling,
           humiliating, mortifying]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "demeaning":
   beneath one, cheap, common, debasing, degrading, deplorable,
   disadvantaged, disgraceful, gutter, humble, humiliating,
   humiliative, in the shade, inferior, infra dig, infra indignitatem,
   junior, less, lesser, low, lower, lowly, minor, modest,
   opprobrious, ordinary, outrageous, pitiful, sad, scandalous,
   second rank, second string, secondary, servile, shameful, shocking,
   sorry, sub, subaltern, subject, subordinate, subservient,
   third rank, third string, too bad, unbecoming, underprivileged,
   unworthy of one, vulgar