A predicative expression (or just predicative) is part of a clause predicate, and is an expression that typically follows a copula or linking verb, e.g. be, seem, appear, or that appears as a second complement (object complement) of a certain type of verb, e.g. call, make, name, etc. The most frequently acknowledged types of predicative expressions are predicative adjectives (also predicate adjectives) and predicative nominals (also predicate nominals). The main trait of all predicative expressions is that they serve to express a property that is assigned to a "subject", whereby this subject is usually the clause subject, but at times it can be the clause object. A primary distinction is drawn between predicative (also predicate) and attributive expressions. Further, predicative expressions are typically not clause arguments, and they are also typically not clause adjuncts. There is hence a three-way distinction between predicative expressions, arguments, and adjuncts.

The terms predicative expression on the one hand, and subject complement and object complement on the other hand overlap in meaning to a large extent.

The most widely acknowledged predicative expressions are adjectives and nominals:

The formulations "over the subject" and "over the object" indicate that the predicative expression is expressing a property that is assigned to the subject or to the object. For example, the predicative expression a thief in the last sentence serves to assign to Jill the property of being a thief. Predicative nominals over subjects are also called predicate nominatives, a term borrowed from Latin grammars and indicating the morphological case that such expressions bear (in Latin).

While the most widely acknowledged predicative expressions are adjectives and nominals, most syntactic categories can be construed as predicative expressions, e.g.

There are, however, certain categories that cannot appear as predicative expressions. Adverbs ending in -ly, for instance, cannot appear as predicative expressions, e.g.

These examples raise the following fundamental question: What characteristic of words and phrases allows or prohibits them from appearing as predicative expressions? The answer to this question is not apparent.

Predicative expressions are not attributive expressions. The distinction is illustrated best using predicative and attributive adjectives: