a low wall built out into the sea to prevent it from washing away sand and stones from the beach Topics Geographyc2丁坝(防止海浪侵蚀海滩砂石的矮墙) Word Originlate 16th cent.: from dialect groin ‘snout’, from Old French groign, from late Latin grunium ‘pig's snout’, from Latin grunnire ‘to grunt’.