grammarization
Grammarization is a term that may appear in discussions of language change, but in most linguistic literature the preferred term is grammaticalization. The word can refer to two related notions: (a) the standardization or codification of a language's grammar through education, policy, or prescriptive norms; or (b) the diachronic process by which lexical items or constructions take on grammatical functions.
In grammaticalization, a lexical item evolves to function as a grammatical marker rather than as a content
Commonly cited examples in English include will, which originated as a verb of volition in Old English
Scholarly work on grammaticalization has been advanced by researchers such as Paul Hopper and Elizabeth Traugott,