The term 'BATMAN'S HIDEOUT' can be solved by the four-letter word 'CAVE'. The CAVE is a secret hideout used by the fictional superhero Batman in the DC Comics universe. It is located in the fictional city of Gotham and serves as a base of operations for Batman's war on crime. The CAVE is equipped with a variety of high-tech gadgets and vehicles, and is often used as a safe haven for Batman and his allies.