There are two competing notions of the predicate, generating confusion concerning the use of the term predicate in general. The first concerns traditional grammar, which tends to view a predicate as one of two main parts of a sentence, the other part being the subject. The purpose of the predicate is to complete an idea about the subject, such as what it does or what it is like. For instance, in a sentence such as Frank likes cake, the subject is Frank and the predicate is likes cake.
This is a companion discussion topic for the original entry at http://grammarerror.com/tags/predicate