grammaticalize

verb (used with object), gram·mat·i·cal·ized, gram·mat·i·cal·iz·ing. Linguistics.

1. to convert (a content word or part of one) into a functor, as in using OE līc, “body,” as a suffix in adjectives and adverbs, such as OE frēondlīc, “friendly.”
2. to represent (semantic features) by grammatical categories, as plurality in English or gender in French.