Cope and Stick
What is Cope and Stick joinery?
Stile & Rail Interlock
The standard for Shaker and raised panel doors. The "stick" is the decorative profile routed along the inside edge of the frame, and the "cope" is the inverse cut on the ends of the rails that allows them to interlock perfectly.
The standard frame-and-panel assembly method where horizontal rails are "coped" to fit the "stick" profile of the stiles.