dado

1. the lower part of the wall of a room, below about waist height, when decorated differently from the upper part.
2. a groove cut in the face of a board, into which the edge of another board is fixed.

   a dado joint

3. the part of a pedestal between the base and the cornice.

mid 17th century (denoting the main part of a pedestal, above the base): from Italian, literally ‘dice or cube’, from Latin datum ‘something given, starting point’ (see datum).