rabbet (n.)

"rectangular groove cut out of the edge of a piece of wood or stone so that it may join by lapping with others," late 14c., from Old French rabat "a recess in a wall, a lower section," literally "a beating down," a back-formation from rabattre "to beat down, beat back" (see rebate (v.)). The verb is attested from mid-15c. (implied in rabetynge).