Source : Webster's Revised Unabridged Dictionary (1913)

Mopboard \Mop"board`\, n. (Carp.)
   A narrow board nailed against the wall of a room next to the
   floor; skirting board; baseboard. See {Baseboard}.

Source : WordNet®

mopboard
     n : a molding covering the joint formed by a wall and the floor
         [syn: {baseboard}, {skirting board}]