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n. Architecture A rectangular court, as:

n. Architecture A usually skylighted central area, often containing plants, in some modern buildings, especially of a public or commercial nature.

n. Architecture The open area in the center of an ancient Roman house.

n. Architecture The forecourt of a building, such as an early Christian church, enclosed on three or four sides with porticoes.

n. 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.

n. A central room or space in ancient Roman homes, open to the sky in the middle; a similar space in other buildings.

n. A square hall lit by daylight from above, into which rooms open at one or more levels.

n. Any enclosed body cavity or chamber

n. An upper chamber of the heart that receives blood from the veins and forces it into a ventricle. In higher vertebrates, the right atrium receives blood from the superior vena cava and inferior vena cava, and the left atrium receives blood from the left and right pulmonary veins.

n. A microscopic air sac within a pulmonary alveolus.

n. A cavity inside a porate aperture of a pollen grain formed by the separation of the sexine and nexine layers, widening toward the interior of the grain.

n.

n. A square hall lighted from above, into which rooms open at one or more levels.

n. An open court with a porch or gallery around three or more sides; especially at the entrance of a basilica or other church. The name was extended in the Middle Ages to the open churchyard or cemetery.

n. The main part of either auricle of the heart as distinct from the auricular appendix. Also, the whole articular portion of the heart.

n. A cavity in ascidians into which the intestine and generative ducts open, and which also receives the water from the gills. See Ascidioidea.

n. A cavity, entrance, or passage

n. In anc. Rom. arch., the entrance-hall, the most important and usually the most splendid apartment of the house.

n. A hall or court resembling in arrangement an atrium proper, as at the entrance of some classical or early Christian public buildings, etc.

n. [NL.] In anatomy, an auricle of the heart, or some equivalent venous cardiac cavity.

n. [NL.] In zoology: The chamber or cavity of ascidians, communicating with the exterior, and with the cavity of the alimentary canal. See atrial, and cut under Tunicata.

n. A membranous saccular diverticulum of the ear in fishes: as, the atrium sinus imparis, a membranous sac given off from the sinus auditorius impar of fishes, and connected in various ways with the air-bladder.

n. the central area in a building; open to the sky

n. any chamber that is connected to other chambers or passageways (especially one of the two upper chambers of the heart)

"The atrium is so charming, it can make it hard to concentrate on the more recent works hosted by the museum."

court    courtyard   

atria    ascidioidea   

atrial    atriate   

cavaedium   

rotunda    foyer    antechamber    plaza    courtyard    stairwell    ballroom    walk-up    piazza    vestibule