subcategorizing

Subcategorizing refers to the linguistic practice of specifying the syntactic requirements a word, especially a verb, imposes on its arguments. In this sense, a subcategorization frame (also called a valency frame) encodes the number, type, and realisation of the elements that a word can accompany in a sentence. Frames describe whether complements are obligatory or optional and what kind of syntactic form they must take, such as noun phrases, prepositional phrases, or clauses.

Frames are commonly categorized by the types of arguments they involve. Monotransitive frames require one object, as in eat an apple. Intransitive frames involve no direct object, as in sleep quietly. Ditransitive frames involve two objects, as in give someone a book (or give a book to someone). Complex-transitive or object-complement frames may include an object followed by another element such as a noun phrase or a clause that renames or describes the object. Optional adjuncts, such as adverbs or location phrases, may enrich the sentence but are not required by the frame.

Subcategorization is closely related to the broader idea of valency, which describes a word’s capacity to combine with other elements. It is distinct from selectional restrictions, which concern semantic plausibility (for example, eat typically takes edible things). In practice, subcategorization frames underpin lexicography, language teaching, and natural language processing, aiding parsing, word sense disambiguation, and the construction of lexical resources like VerbNet. Subcategorizing differs across languages, reflecting variations in how arguments are realized syntactically.