From Old French brosse 'brushwood, bundle of twigs' — the first brushes were literally bundles of twigs.
A tool with bristles, wire, or other filaments used for cleaning, grooming, or painting.
From Old French broisse, brosse 'brush, brushwood,' probably from Vulgar Latin *bruscia 'bundle of twigs.' The original brush was a bundle of twigs or bristles tied together. The word may ultimately be of Germanic origin. The verb 'to brush' followed