a·tri·um (ā'trē-əm)
n., pl., a·tri·a (ā'trē-ə), or -ums.

1. Architecture. A rectangular court, as:
   1. A usually skylighted central area, often containing plants, in some modern buildings, especially of a public or commercial nature.
   2. The open area in the center of an ancient Roman house.
   3. The forecourt of a building, such as an early Christian church, enclosed on three or four sides with porticoes.
2. Anatomy. A body cavity or chamber, especially either of the upper chambers of the heart that receives blood from the veins and forces it into a ventricle. Also called auricle.

[Latin ātrium.]

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The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.

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