資料來源 : Webster's Revised Unabridged Dictionary (1913)

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.

   2. Unwillingness to hear; voluntary rejection of what is
      addressed to the understanding.

   {Nervous deafness}, a variety of deafness dependent upon
      morbid change in some portion of the nervous system,
      especially the auditory nerve.