A predicate is a grammatical term that refers to the part of a sentence or clause that expresses what is said about the subject. It typically includes the verb and any objects or modifiers associated with it. For example, in the sentence "The cat sleeps on the mat," "sleeps on the mat" is the predicate, providing information about what the subject (the cat) is doing. In logical terms, a predicate can also refer to a function that returns true or false based on the input values.