atrium

atrium   Architecture.  1. an open courtyard within a house.an open courtyard within a house. 2. a multistoried court or hall within a hotel or other building, usually having a skylight.a multistoried court or hall within a hotel or other building, usually having a skylight.  Medicine. a chamber that gives entrance to another structure or organ; usually used alone to refer to an atrium of the heart.