A poolroom is a room where people play pool — the table game with balls and a long stick, not swimming. You find it in a bar, a club, or a hall that is mainly for that game. It is everyday, slightly rough-around-the-edges language, more American than British; British speakers often say pool hall. In films the poolroom is a back room with a table, talk, and sometimes smoke. Though actually, in older American stories a poolroom could also be a place for betting, but this entry is the room for the game. It is not fancy hotel English.