breakwater, groin, groyne, mole, bulwark, seawall, jetty
['buckeye, horse chestnut, conker', 'passenger car, coach, carriage', 'shield, buckler', 'scabbard', 'chain mail, ring mail, mail, chain armor, chain armour, ring armor, ring armour', 'dugong, Dugong dugon', 'organ, pipe organ']