A joint made by a tongue (a rib on one edge of a board) that fits into a corresponding groove in the edge of another board to make a tight flush joint. Typically, the subfloor plywood is tongue-and-groove.
Wooden boards with a groove along one edge and a protruding tongue down the other. The tongue slots into the groove of an adjacent piece for a secure fixing.
The configuration of the meeting rails that differs from shiplap in having matching channel groove and protrusion on the longitudinal edges of the abutting meeting rails for wind and weather protection.