Lewis & Short

ātrĭŏlum, i, n. dim. [atrium], a small hall, an antechamber, Cic. ad Q. Fr. 3, 1, 1; id. Att. 1, 10, 3; Inscr. Orell. 4509; Vulg. Ezech. 46, 21 bis; 46, 22; 46, 23.