bulwark

noun

1
a protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away
2
a fencelike structure around a deck (usually plural)
3
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

Also useful for “bulwark”:Scrabble— High-value letters — see what it scores