Source : Webster's Revised Unabridged Dictionary (1913)

Dissemble \Dis*sem"ble\, v. t. [imp. & p. p. {Dissembled}; p.
   pr. & vb. n. {Dissembling}.] [OF. dissembler to be
   dissimilar; pref. dis- (L. dis-) + F. sembler to seem, L.
   simulare to simulate; cf. L. dissimulare to dissemble. See
   {Simulate}, and cf. {Dissimulate}.]
   1. To hide under a false semblance or seeming; to feign
      (something) not to be what it really is; to put an untrue
      appearance upon; to disguise; to mask.

            Dissemble all your griefs and discontents. --Shak.

            Perhaps it was right to dissemble your love, But --
            why did you kick me down stairs?      --J. P.
                                                  Kemble.

   2. To put on the semblance of; to make pretense of; to
      simulate; to feign.

            He soon dissembled a sleep.           --Tatler.

   Syn: To conceal; disguise; cloak; cover; equivocate. See
        {Conceal}.

Dissemble \Dis*sem"ble\, v. i.
   To conceal the real fact, motives, ?tention, or sentiments,
   under some pretense; to assume a false appearance; to act the
   hypocrite.

         He that hateth dissembleth with his lips. --Prov. xxvi.
                                                  24.

         He [an enemy] dissembles when he assumes an air of
         friendship.                              --C. J. Smith.

Source : WordNet®

dissemble
     v 1: make believe with the intent to deceive; "He feigned that he
          was ill"; "He shammed a headache" [syn: {feign}, {sham},
           {pretend}, {affect}]
     2: hide under a false appearance; "He masked his
        disappointment" [syn: {cloak}, {mask}]
     3: behave unnaturally or affectedly; "She's just acting" [syn:
        {pretend}, {act}]