Found:

Polysemy

MORPHOLOGY: the phenomenon that a word acquires new usages which, over time, are likely to become more like new meanings. EXAMPLE: the English word mouth refers first of all to the opening of the buccal cavity, but next to this it refers to the point where a river joins the sea.

LIT.	Aronoff, M. (1976) Spencer, A. (1991)

SEMANTICS: the phenomenon that a word has several different meanings which are closely related to each other. The ambiguity of church (either a building or an institution) is an instance of polysemy.