In linguistics, selection denotes the ability of predicates to determine the semantic content of their arguments. Predicates select their arguments, which means they limit the semantic content of their arguments. A distinction may sometimes be drawn between types of selection; viz., s(emantic)-selection versus c(ategory)-selection. Selection in general stands in contrast to subcategorization: selection is a semantic concept, whereas subcategorization is a syntactic one; predicates both select and subcategorize for their complement arguments, but only select their subject arguments.

Selection is closely related to valency, a term used in grammars other than the Chomskian generative grammar for a similar phenomenon.

The following pairs of sentences illustrate the concept of selection; the # indicates semantic deviance:

The predicate is wilting selects a subject argument that is a plant or is plant-like. Similarly, the predicate drank selects an object argument that is a liquid or is liquid-like. A building cannot normally be understood as wilting, just as a car cannot normally be interpreted as a liquid. The b-sentences are possible only given an unusual context that establishes appropriate metaphorical meaning. The deviance of the b-sentences is thus attributed to violation of those selectional restrictions determined by the predicates is wilting and drank.

When a mismatch between a selector and a selected element triggers reinterpretation of the meaning of those elements, that process is referred to as coercion.

One sometimes encounters the terms s(emantic)-selection and c(ategory)-selection. The concept of c-selection overlaps to an extent with subcategorization. Predicates c-select the syntactic category of their complement arguments—e.g., noun (phrase), verb (phrase), adjective (phrase), etc.; that is, they determine the syntactic category of their complements. In contrast, predicates s-select the semantic content of their arguments; thus, s-selection is a semantic concept, whereas c-selection is a syntactic one. (Note that when the terms selection and selectional restrictions appear without the c- or s- prefixes, they are usually understood to refer to s-selection.)

The b-sentences above do not contain violations of the c-selectional restrictions of the predicates is wilting and drank; they are, rather, well-formed from a syntactic point of view (hence #, not *), for the arguments the building and a car satisfy the c-selectional restrictions of their respective predicates (i.e., in this case, the arguments are required to be nouns or noun phrases). Only the s-selectional restrictions of the predicates is wilting and drank are violated in the b-sentences.

Selectional constraints or selectional preferences describe the degree of s-selection, in contrast to selectional restrictions, which treat s-selection as a binary yes-or-no. Selectional preferences have often been used as a source of linguistic information in natural language processing applications. Thematic fit is a measure of how much a particular word in a particular role (like subject or direct object) matches the selectional preference of a particular predicate. For example, the word cake has a high thematic fit as a direct object for cut.