The Collaborative International Dictionary of English v.0.48:

Sarcoma \Sar*co"ma\, n.; pl. L. Sarcomata (# or #), E.
   sarcomas. [NL., from Gr. ?, from sa`rx, sa`rkos, flesh.]
   (Med.)
   A tumor of fleshy consistence; -- formerly applied to many
   varieties of tumor, now restricted to a variety of malignant
   growth made up of cells resembling those of fetal development
   without any proper intercellular substance.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sarcoma
    n 1: a usually malignant tumor arising from connective tissue
         (bone or muscle etc.); one of the four major types of
         cancer

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "sarcoma":
   benign tumor, callosity, callus, cancer, carcinoma, corn, cyst,
   excrescence, fungosity, fungus, growth, intumescence,
   malignant growth, metastatic tumor, mole, morbid growth, neoplasm,
   nevus, nonmalignant tumor, outgrowth, proud flesh, tumor, verruca,
   wart, wen