'ARCHIVAULT, noun [arch, chief, and vault.] In building, the inner contour of an arch, or a band adorned with moldings, running over the faces of the arch-stones, and bearing upon the imposts. It has only a single face in the Tuscan order; two faces crowned in the Doric and Ionic, and the same moldings, as the architrave, in the Corinthian and Composite.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI