What does "washboard" mean?

Washboard: A board running round, and serving as a facing for, the walls of a room, next to the floor; a mopboard.

Additional senses

  1. 2.(Naut.) A broad, thin plank, fixed along the gunwale of boat to keep the sea from breaking inboard; also, a plank on the sill of a lower deck port, for the same purpose; -- called also wasteboard. Mar. Di

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