adjective
Definition: Relating to a grammatical construction where a noun or noun phrase is placed next to another noun for clarification or identification.
Example: In the sentence 'My brother, a doctor, lives in New York', the phrase 'a doctor' is an appositive that gives more information about 'my brother'.
noun
Definition: A word or phrase that is placed next to another word to explain or identify it more clearly.
Example: In the sentence 'My brother, a talented musician, plays the guitar', 'a talented musician' is an appositive that describes 'my brother'.