Haunched Tenon
What is a 'Haunched' tenon?
Blind Frame Joinery
An advanced version of the mortise and tenon used in high-end paneling. A small "haunch" or shoulder is left on the tenon to fill the groove used for the panel, preventing the joint from twisting over time.
A specialized tenon with a "step" or haunch that prevents the rail from twisting while hiding the mortise groove.