Source : Webster's Revised Unabridged Dictionary (1913)

Neoplasm \Ne"o*plasm\, n. [See {Neoplasia}.] (Physiol. & Med.)
   A new formation or tissue, the product of morbid action.

Source : WordNet®

neoplasm
     n : an abnormal new mass of tissue that serves no purpose [syn:
         {tumor}, {tumour}]