functional category

A type of CATEGORY recognized in GOVERNMENT-BINDING THEORY, illustrated by INFL (INFLECTION, often abbreviated as I), Comp (COMPLEMENTIZER, C), and Det (DETERMINER, D). IP, CP and DP are the corresponding functional projections. (I and IP are referred to as T (tense) and TP in more recent literature.) Functional categories are not required to contain overt PHONETIC content, but some may be present in the form of MORPHOLOGICAL realizations, such as English third-person -s.