<unk> a (new growth in Greek) is the abnormal proliferation of cells, resulting in a<unk> .  <unk> a is the scientific term for the group of diseases commonly called tumor or cancer. 
Because<unk> a includes very different diseases, it is difficult to find a definition that describe them all. The definition of the British oncologist R.A. Willis is widely cited:
A<unk>  is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues, and persists in the same excessive manner after cessation of the stimulus which evoked the change.
Neoplasm
Cancer Cell
Biomedical tissue
Calculus 
Biological pigment
Tissue 
Contractility
Thrombosis