Source : Webster's Revised Unabridged Dictionary (1913)

Teratoma \Ter`a*to"ma\, n. [NL., fr. Gr. ?, ?, monster + -oma.]
   (Med.)
   A tumor, sometimes found in newborn children, which is made
   up of a heterigenous mixture of tissues, as of bone,
   cartilage and muscle.

Source : WordNet®

teratoma
     n : a tumor consisting of a mixture of tissues not normally
         found at that site