The Collaborative International Dictionary of English v.0.48:

Deafness \Deaf"ness\, n.
   1. Incapacity of perceiving sounds; the state of the organs
      which prevents the impression which constitute hearing;
      want of the sense of hearing.
      [1913 Webster]

   2. Unwillingness to hear; voluntary rejection of what is
      addressed to the understanding.
      [1913 Webster]

   Nervous deafness, a variety of deafness dependent upon
      morbid change in some portion of the nervous system,
      especially the auditory nerve.
      [1913 Webster]

WordNet (r) 3.0 (2006):

deafness
    n 1: partial or complete loss of hearing [syn: deafness,
         hearing loss]