Baseboard n. (Arch.) A board, or other woodwork, carried round the walls of a room and touching the floor, to form a base and protect the plastering; also called washboard (in England), mopboard, and scrubboard.
... panelled wainscotting, painted white, is installed. Because of the unevenness of the floor, the height of this wainscotting varies from 4 feet 2 inches to 4 feet 3 inches. Its panels are of varying width, from 3 to 6 inches, and are beaded. At the base of the wainscotting is a 5-inch baseboard. ... — The Fairfax County Courthouse • Ross D. Netherton