noun \ˈā-trē-əm\

: an open area inside a tall building that has windows to let light in from above

: one of two sections of the heart that take in blood from the veins

plural atria \-trē-ə\ also atri·ums

Full Definition of ATRIUM

:  the central room of a Roman house
plural usually atriums
a :  a rectangular open patio around which a house is built
b :  a many-storied court in a building (as a hotel) usually with a skylight
[New Latin, from Latin] :  an anatomical cavity or passage; especially :  the chamber or either of the chambers of the heart that receives blood from the veins and forces it into the ventricle or ventricles — see heart illustration
atri·al \-trē-əl\ adjective

Origin of ATRIUM

First Known Use: 1577


noun \ˈā-trē-əm\   (Medical Dictionary)
plural atria \-trē-ə\ also atri·ums

Medical Definition of ATRIUM

: an anatomical cavity or passage; especially : a chamber of the heart that receives blood from the veins and forces it into a ventricle or ventricles


noun    (Concise Encyclopedia)

Atrium of the basilica of Sant'Ambrogio, Milan, 1088–1128.—Alinari/Art Resource, New York

In an ancient Roman house, an open central court that contained the impluvium, a basin where rainwater collected. It originally contained the hearth and functioned as the center of family life. The term later came to be used for the open front courtyard of a Christian basilica, where congregants collected before services. The atrium was revived in the 20th century in the form of glass-covered, greenery-filled multistory spaces sometimes found in shopping centers, office buildings, and large hotels.


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