The definition of a predicate adjective is very similar. A predicate adjective is an adjective that modifies, or tells more about the subject of a sentence. If I say
The chair is orange, the subject is “the chair” while “orange” modifies the subject. Of course, they are connected by the linking verb, is. Remember, an adjective answers the question: which one, what kind, or how many and it always modifies, or tells more about, a noun or another adjective.
So, linking verbs can also connect the subject to a predicate noun or a predicate adjective.