trunk road(n = noun.artifact) highroad - a highway;
is a kind of highway, main road

access road, arterial road, atrioventricular trunk, automobile trunk, bridle road, celiac trunk, frontage road, high road, hit the road, jinny road, local road, macadam road, main road, middle of the road, on the road, post road, private road, pulmonary trunk, ring road, road, road agent, road builder, road construction, road game, road gang, road hog, road map, road mender, road metal, road rage, road roller, road runner, road sense, road show, road surface, road test, road to damascus, royal road, service road, side road, silk road, skid road, slip road, take the road, tree trunk, trunk, trunk call, trunk engine, trunk hose, trunk lid, trunk line, trunk piston, trunk route, trunk steamer