IPA: //ˈwɔːʃbɔːrd//
KK: /ˈwɔːʃbɔːrd/
A flat board with a ridged surface used for washing clothes by rubbing them against it.
She used a washboard to scrub the dirt out of her clothes.
Washboard → The word is formed from "wash" (from Old English *wæscan*, meaning to cleanse or wash) and "board" (from Old English *bord*, meaning a flat piece of wood or surface). A washboard is a flat surface used for washing clothes, typically made of wood or metal.
Think of the action of 'washing' ('wæscan') on a 'board' ('bord') — that's why a washboard is a tool used for washing clothes.