What does "atrium" mean?

Atrium: (Anat.) The main part of either auricle of the heart as distinct from the auricular appendix. Also, the whole articular portion of the heart.

Additional senses

  1. 2.(Zoöl.) A cavity in ascidians into which the intestine and generative ducts open, and which also receives the water from the gills. See Ascidioidea.

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