Lewis & Short

trĭcămĕrātus, a, um, adj. [tres-camera], having three chambers (late Lat.). ecclesia, Aug. Civ. Dei, 15, 26: inferiora ar cae bicamerata et tricamerata facies, Ambros. Hexaëm. 6, 9, n. 72.
Subst.: trĭcă-mĕrātum, i, n., a room divided into three chambers, Hier. adv. Jovin. 1, 17.