Lewis & Short

bĭcămĕrātus, a, um, adj. [bis-camera], with a double vault, doubly arched: cella, Hier. ad Jovin. 1, 17: ecclesia, Aug. Civ. Dei, 15, 26.
As subst.: bĭcămĕrātum, i, n., a receptacle with two compartments, Ambros. Hexaëm. 6, 9, 72.