n. A usually rectangular cavity in a piece of wood, stone, or other material, prepared to receive a tenon and thus form a joint.n. Printing A hole cut in a plate for insertion of type.v. To join or fasten securely, as with a mortise and tenon.v. To make a mortise in.v. Printing To cut a hole in (a plate) for the insertion of type.v. Printing To cut such a hole and insert (type).