1. a structure built out into the sea or a river to protect a coast or harbor from erosion or to control water flow
Usage: also spelled 'groin' in U.S. English; commonly used in coastal engineering and geography

Examples

• The groyne extends from the beach into the water to prevent sand erosion.
• Engineers built several groynes along the coastline to protect the town from storms.
• Tourists walked along the groyne to get a better view of the harbor.
• The old groyne was damaged during the winter and required repairs.
• Groynes help trap sediment and build up the beach over time.