Definition of metastasis:
(n) :
the tranferrence of a bodily function or
disease to another part of the
body, specifically the development of a secondary area of disease remote from the original site, as with some
cancers
"1963: Stayed in her own house, searched her body each morning and examined her conscience each night for progressive symptoms of the metastasis she feared was in her. -- Thomas Pynchon, V."