A predicate noun is a single noun or a noun phrase that renames the subject of a sentence and follows a form of the verb "to be" or another linking verb. Forms of the verb "to be" include:
is, was, am, are, be, being, been, has been, may be, and were
Other verbs that may be linking verbs or action verbs include:
smell, taste, feel, sound, grow, seem, remain, become, continue, appear, turn, and stay
Examples of sentences with the predicate nouns underlined are:
A predicate noun is also called a completer, or complement, because it completes the verb. The verb in this case is called an intransitive verb and must be followed by a noun or noun phrase. This noun or noun phrase completes the meaning of the sentence. Every sentence has a subject and a predicate, so the intransitive verb and the predicate noun make up the predicate of the sentence.
Since you now understand predicate nouns, you may be interested to learn a bit about predicate adjectives. Adjectives modify nouns, which includes describing them and giving more information about them, like their composition, their origin, your opinion of them and their purpose.
A predicate adjective is very similar to a predicate noun in that it completes the predicate and follows an intransitive verb. These are verbs like:
am, is, was, were, has been, are, smell, remain, seem, sound, stay, continue, become, and grow
Instead of renaming the subject, it modifies it. Here are some sentences with the predicate adjective underlined.