atrium

Originally, the main central court of a Roman house which was open to the air, this word has several, specific meanings.

It is the central, glass-roofed hall that can extend through several storeys in a building such as a shopping centre or hotel.

Atrium also referred to a court in front of an early Christian or medieval church, especially those flanked by colonnades.

In medical contexts, it refers to a cavity or chamber in the body such as the chambers of the heart.