ˈā.trēəm also especially in senses 1 & 2 ˈä.- noun
( plural atria -ēə)
Etymology: Latin
1. : the central hall of a Roman house
2.
a. : the open court leading to a basilica or dwelling having a covered way on three or (as in a cloister) on all four sides
b. : a square hall from which other rooms open and which is used as a sitting room in a modern house
3.
[New Latin, from Latin]
: an anatomical cavity or chamber: as
a. : the chamber or one of the two chambers of the heart by which the blood is received from the veins and forced into the ventricle or ventricles and which in man consists of a main cavity and an auricular appendage
b. : the main part of the tympanic cavity
4.
[New Latin, from Latin]
: an anatomical entrance or passage:
a. : an external chamber in tunicates and lancelets that receives water from the gills
b. : a vestibule in various insects from which one or more tracheae extend into the body