[1] : The Collaborative International Dictionary of English v.0.48

malignant tumor \malignant tumor\ n. med.,
   same as malignancy4.

   syn: malignancy, malignance, malignant tumor, metastatic
        tumor.
        wordnet 1.5

[2] : The Collaborative International Dictionary of English v.0.48

tumor \tu"mor\ t=u"m~er, n. l., fr. tumere to swell: cf.
   f. tume'ur. see tumid.
   1. med. a morbid swelling, prominence, or growth, on any
      part of the body; especially, a growth produced by
      deposition of new tissue; a neoplasm.
      1913 webster

   2. affected pomp; bombast; swelling words or expressions;
      false magnificence or sublimity. r.
      1913 webster

            better, however, to be a flippant, than, by a
            revolting form of tumor and perplexity, to lead men
            into habits of intellect such as result from the
            modern vice of english style.         --de quincey.
      1913 webster

   encysted tumor, a tumor which is inclosed in a membrane
      called a cyst, connected with the surrounding parts by the
      neighboring cellular substance.

   fatty tumor. see under fatty.

   innocent tumor, or benign tumor, one which does not of
      itself threaten life, and does not usually tend to recur
      after extirpation; a tumor which has not metastesized.

   malignant tumor, a tumor which tends continually to spread,
      to become generalized in different parts of the body, and
      to recur after extirpation, and which, if left to itself,
      causes death.
      1913 webster
see also:
tumid encysted tumor fatty tumor fatty innocent tumor benign tumor 
malignant tumor 

[3] : WordNet (r) 2.0

malignant tumor
     n : a tumor that is malignant and tends to spread to other parts
         of the body syn: malignant neoplasm, metastatic tumor
see also:
malignant neoplasm metastatic tumor 

Malignant Tumor >> M Words
Malignant Tumor, definition of term: Malignant Tumor
malignant+tumor_pag1.html

Tumor >> T Words
Tumor, definition of term: Tumor
tumor_pag1.html

Malignant >> M Words
Malignant, definition of term: Malignant
malignant_pag1.html

Malignant Melan >> M Words
Malignant Melan, definition of term: Malignant Melan
malignant+melan_pag1.html

Brain Tumor >> B Words
Brain Tumor, definition of term: Brain Tumor
brain+tumor_pag1.html

Benign Tumor >> B Words
Benign Tumor, definition of term: Benign Tumor
benign+tumor_pag1.html