Metastasis

noun

1. A change in nature, form, or quality.
2. The transference 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.
3. The spread of a harmful event to another location, like the metastasis of a cancer.
4. Denying adversaries' arguments and turning the arguments back on them.