Casino Definition–noun, plural -nos for 1. | 1. | a building or large room used for meetings, entertainment, dancing, etc., esp. such a place equipped with gambling devices, gambling tables, etc. | | 2. | (in Italy) a small country house or lodge. | | 3. | Also, cassino. Cards. a game in which cards that are face up on the table are taken with eligible cards in the hand. | |