In a mortise and tenon joint, the mortise should be slightly deeper than the tenon. Which term correctly completes the sentence?

• A. Mortise
• B. Dowel
• C. Shoulder
• D. Tenon

Answer: (C)

The important idea is how the joint seats and bears. In a mortise and tenon, the depth of the mortise is set so that the tenon’s bearing area can sit firmly against the mortise walls and shoulders when the joint is assembled. The term that fits here describes that bearing area on the tenon—the shoulder. If the mortise is cut a bit deeper than the tenon shoulder, the tenon can be fully inserted and the shoulder will seat against the mortise faces, giving a tight, square joint with proper glue surfaces. The other parts listed—the hole, a separate pin, or the projecting tenon itself—don’t describe this seating relationship.