lunge line noun2 •A rope-like piece of equipment, usually 20 meters or longer in length, attached to the bridle, longeing cavesson, or halter of a horse to provide control while longeing. •(UK) A rope-like piece of equipment, usually 20 feet or longer in length, attached to the bridle, lungeing cavesson, or halter of a horse to provide control while lungeing. formslunge lines