Source : Webster's Revised Unabridged Dictionary (1913)

Melanism \Mel"a*nism\, n. (Ethnol.)
   The character of having a high degree of pigmentation, as
   shown in dark skin, eyes, and hair.

Melanism \Mel"a*nism\ (m[e^]l"[.a]*n[i^]z'm), n. [Gr. me`las,
   -anos, black.]
   1. An undue development of dark-colored pigment in the skin
      or its appendages; -- the opposite of albinism.

   2. (Med.) A disease; black jaundice. See {Mel?na}.

Source : WordNet®

melanism
     n : a condition characterized by abnormal deposits of melanin
         (especially in the skin) [syn: {melanosis}]