bulwark

Noun

• a protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away

• a fencelike structure around a deck (usually plural)

• an embankment built around a space for defensive purposes
  • they stormed the ramparts of the city
    
  • they blew the trumpet and the walls came tumbling down
    

Verb

• defend with a bulwark

Related words

• Synonyms: 
  breakwater , groin , groyne , mole , seawall , jetty , rampart , wall