predicate adjective / predicate nominative
The complement after a linking verb.
After a linking verb, an adjective is a predicate adjective: The hall is cold. A noun is a predicate nominative: Dana is the clerk. Use the adjective form after the linking verb, not an adverb, when you describe the subject.
Examples
Use The coffee tastes bitter.
Use Ruiz is the director.
Avoid The coffee tastes bitterly.