Source : Webster's Revised Unabridged Dictionary (1913)

Deaden \Dead"en\, v. t. [imp. & p. p. {Deadened}; p. pr. & vb.
   n. {Deadening}.] [From {Dead}; cf. AS. d?dan to kill, put to
   death. See {Dead}, a.]
   1. To make as dead; to impair in vigor, force, activity, or
      sensation; to lessen the force or acuteness of; to blunt;
      as, to deaden the natural powers or feelings; to deaden a
      sound.

Source : WordNet®

deadening
     adj : so lacking in interest as to cause mental weariness; "a
           boring evening with uninteresting people"; "the
           deadening effect of some routine tasks"; "a dull play";
           "his competent but dull performance"; "a ho-hum speaker
           who couldn't capture their attention"; "what an irksome
           task the writing of long letters is"- Edmund Burke;
           "tedious days on the train"; "the tiresome chirping of
           a cricket"- Mark Twain; "other people's dreams are
           dreadfully wearisome" [syn: {boring}, {dull}, {ho-hum},
            {irksome}, {slow}, {tedious}, {tiresome}, {wearisome}]
     n : the act of making something futile and useless (as by
         routine) [syn: {stultification}, {constipation}, {impairment}]