Functional projection

In X-bar theory, a functional projection is the projection of a functional head, such as COMP (CP), INFL (IP), or Det (DP). The underlying assumption is that, like the lexical heads N, A, V and P, functional heads have a syntactic projection as dictated by X-bar theory.

Comment
A fundamental question is whether there is a limit to the number of functional categories. It seems reasonable to assume that their projection is in some sense parasitic on, or an extension of, a lexical projection.

Link
Utrecht Lexicon of Linguistics

Other languages
German funktionale Projektion