weatherboard noun 3verb 1forms 3 noun3 •A plank placed over an opening to keep out driven water. •Any of a series of horizontal boards used to cover the exterior of a timber-framed building; clapboard.The homestead lies half a mile from the road, a small bungalow built of weatherboard with an iron roof and with verandas on three sides […] — 1952 •The windward side of a vessel. verb1 •To cover with a weatherboard. formsweatherboarded · weatherboarding · weatherboards