The Collaborative International Dictionary of English v.0.48:

malignant melanoma \malignant melanoma\ n. (Med.),
   Any of several malignant neoplasms (usually of the skin)
   consisting of melanocytes; called also melanoma. It is
   classed as a type of skin cancer.
   [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Melanoma \Mel`a*no"ma\, n.; L. pl. -nomata. [NL.; Gr. ?, ?,
   black + -oma.] (Med.)
   (a) A tumor containing dark pigment. Such tumors are usually
       malignant and often fatal.
   (b) Development of dark-pigmented tumors.
       [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

melanoma
    n 1: any of several malignant neoplasms (usually of the skin)
         consisting of melanocytes [syn: melanoma, malignant
         melanoma]