-ˌvüˈsu̇(ə)r noun
( -s )
Etymology: French, literally, rear arching, from arrière rear, behind + voussure arching, bend of an arch, from (assumed) Vulgar Latin volsura, from volsus (past participle of Latin volvere to roll) + Latin -ura -ure — more at voluble
1. : an inner or rear arch in a thick wall that carries the inner part of that wall ; especially : such an arch over a door or window frame
2. : a relieving arch behind the face of a wall