dado.
1. Die or flat-faced plain block of a Classical pedestal between the base and cap.

2. Surface of an internal wall like an extended pedestal all the way round a room between a chair-rail (cornice), and skirting (base or plinth), called a chair- or dado-rail. A panelled timber dado is called a wainscot. Dado is not used to describe an external pedestal-course.

3. To cut or form with a groove of rectangular section, so the rectangular groove itself is also called a dado.

da·do / ˈdādō/ • n. (pl. -dos) the lower part of the wall of a room, if it has a different color or covering than the upper part. ∎  a groove cut in the face of a board, into which the edge of another board is fixed. ∎ Archit. the part of a pedestal between the base and the cornice.

dado cubical block of a pedestal XVII; lining along the lower part of a wall XVIII. — It. dado die, cube (= F. dé DIE 2).