All 6 Uses of

atrium
in
Nineteen Minutes

There was a new green metal roof, fresh grass growing out front, and a glass atrium that rose two stories at the rear of the school.†
Chpt 2

Instead, now, there was an enormous glass atrium that covered the spot where the gymnasium and locker room had been.†
Chpt 2 *

Unlike the rest of the seats in the atrium, these had backs and were painted white.†
Chpt 2

She noticed that the maple tree, the one that had grown outside the window of the second-story locker room, had not been cut down during the construction of the atrium.†
Chpt 2

They walked out of the atrium in silence, down the corridors, past the rows of cubbies.†
Chpt 2

Definitions:

(1) (atrium as in: atrium of the building)
a large public room leading to other rooms--often skylit and containing plants and/or water features

or in ancient architecture:

a roofless area of a building--such as the center of a Roman house or an entry courtyard surrounded by roofed columns in an ancient Christian church
(2) (atrium as in: right atrium of the heart)
chamber from which blood enters the heart
(3) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Much less commonly, atrium can refer to anatomical structures other than the heart.