What is "subcategorization"

n. 1 Placing something into a subcategory. 2 (context grammar English) The practice of specifying what types of complements a word may take when that word acts as the head of a phrase of a certain category; this specification restricts the wordʼs category, making it smaller, hence a “subcategory” of the wordʼs category.

In linguistics, subcategorization denotes the ability/necessity for lexical items (usually verbs) to require/allow the presence and types of the syntactic arguments with which they co-occur. The notion of subcategorization is similar to the notion of valency, although the two concepts (subcategorization and valency) stem from different traditions in the study of syntax and grammar.