(in fortification) an opening, as a loophole or crenel, through which missiles may be discharged.
Architecture. a splayed enlargement of a door or window toward the inner face of a wall.
Dentistry. the space between adjacent teeth.
Origin of embrasure
1695-1705; < French, equivalent to embras(er) to enlarge a window or door opening, make an embrasure (apparently the same v. as embraser to set on fire (see embrace2), though sense shift unclear) + -ure-ure