washboardnoun [ C ]
/ˈwɒʃˌbɔːd//ˈwɑːʃˌbɔːrd/washboard noun [ C ] (FOR WASHING)
a board with a series of raised wood or metal lines on it, used in the past when washing clothes. The clothes were rubbed against the board to help clean them.
washboard noun [ C ] (INSTRUMENT)
a similar board used as a simple musical instrument that is rubbed or hit