Synonyms for Bulwark (same or very similar meaning)
WordNet sense 1 (an embankment built around a space for defensive purposes):
rampart, wallWordNet sense 2 (a protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away):
breakwater, groin, jetty, mole, seawall, groyne, moleFrom the ODE community, based on WordNetadd/edit