A recreation room or rec room was a space in a starship where crew could relax while off-duty. A larger space with facilities for games or sports was referred to as a rec deck. Rec rooms might have food slots or replicators.
The USS Enterprise had several small rec rooms and a rec deck with gym and dojo amongst other things. After the refit it also had a large rec dec on deck 7, where James Kirk delivered his V'ger briefing, and an officers' lounge. (TOS, Star Trek: The Motion Picture)