- A square hall lighted from above, into which rooms open at
one or more levels. - 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. - The main part of either auricle of the heart as distinct
from the auricular appendix. Also, the whole articular portion of the
heart. - A cavity in ascidians into which the intestine and
generative ducts open, and which also receives the water from the
gills. See Ascidioidea.