relish
In a wooden frame: the projection or shoulder around, or at the side of, a tenon (“projecting member made to insert into a mortise”), used to strengthen a mortise-and-tenon joint.
relish: the step that stops a tenon going too far
In mortise-and-tenon joinery, a relish is a stepped shoulder cut into the side or end of a tenon. It bears against the edge of the mortise hole, preventing the tenon from being driven too deep into the joint and locking the two pieces in precise alignment. The relish acts as a mechanical stop and strengthens the joint by distributing stress across a larger contact area than the tenon alone would provide.
The relish is cut as a rectangular step on one or more faces of the tenon. If the tenon is 12 mm thick and passes through a 20 mm thick rail, for example, the relish might be 3 to 5 mm deep, running the full width of the tenon. When the joint is assembled, the relish face sits flush against the inner surface of the mortise hole, bearing the shear loads that would otherwise concentrate at the tenon's tip.
When relishes matter most
Relishes are essential in through mortise-and-tenon joints, where the tenon passes completely through the receiving piece and must be trimmed flush afterward. Without a relish, a through tenon can be hammered too far and split the far side of the wood. They are also used in blind mortises where alignment and depth control are critical, particularly in frame-and-panel doors, chair legs, and table aprons that will experience repeated racking stresses.
A relish can be cut on a single face (the most common case) or on opposite faces for extra strength in high-stress joints. In frame joinery, a relish on the outside face of a rail tenon helps hide the joint line by allowing the rail to seat tightly against the stile. Furniture makers often size relishes conservatively to avoid weakening the tenon itself: the step must be large enough to function as a stop but not so large that it becomes a stress concentration.
The term relish likely derives from the French relief, meaning a raised projection or ledge. It has been standard vocabulary in English carpentry since at least the 18th century and appears in period joiners' accounts and design books. Modern CNC machines cut relishes with precision, but hand chiseling them remains a common practice in traditional work, where the craftsperson must carefully undercut the mortise to accept the step without gaps.