An adjective complement is a phrase that modifies or adds meaning to an adjective. It always follows the adjective and is either a noun clause or prepositional phrase. Some examples of sentences with adjective complements underlined are "She was hesitant to tell her parents" and "Are you afraid of spiders?". In addition to adjective complements, there are also subject complements, object complements, and verb complements that can modify nouns and verbs.