v. t. [ imp. & p. p. Deadened p. pr. & vb. n. Deadening. ] [ From Dead; cf. AS. d&unr_;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. [ 1913 Webster ]

As harper lays his open palm
Upon his harp, to deaden its vibrations. Longfellow. [ 1913 Webster ]

2. To lessen the velocity or momentum of; to retard; as, to deaden a ship's headway. [ 1913 Webster ]

3. To make vapid or spiritless; as, to deaden wine. [ 1913 Webster ]

4. To deprive of gloss or brilliancy; to obscure; as, to deaden gilding by a coat of size. [ 1913 Webster ]

5. To render impervious to sound, as a wall or floor; to deafen. [ Webster 1913 Suppl. ]

n. One who, or that which, deadens or checks. [ 1913 Webster ]

adj. [ p. pr. of verb deaden{ 3 }. ] Rendering less lively, intense, or vigorous; as, the deadening effect of some routine tasks. [ WordNet 1.5 ]

2. So lacking in interest as to cause mental weariness; as, the deadening effect of some routine tasks.
Syn. -- boring, dreary, ho-hum, irksome, tedious, tiresome, wearisome. [ WordNet 1.5 ]

n. The act of making something futile and useless (as by routine).
Syn. -- stultification, impairment. [ WordNet 1.5 ]