Gordon's bedroom, the messiest room in the house, is filled with empty pizza boxes and dirty clothes. What is the appositive phrase in the sentence? Gordon's bedroom the messiest room in the house is filled with empty pizza boxes and dirty clothes

The appositive phrase in this sentence is the one between commas "the messiest room in the house"

Explanation:

An appositive phrase provides more information, renames or identifies the previous noun or noun phrase. In this case it identifies Gordon's room as the messiest room.