Hidden Retreat is a term used to describe a secret or secluded place, such as a cave, a bunker, or a secret hideaway. The term can also be used to refer to a place of refuge or safety. In the crossword puzzle, the solution for the term Hidden Retreat was 'LAIR, ' which is a synonym for a hidden retreat. A LAIR is typically a den or a hideout, and it is often associated with animals or villains in literature and film.