a solid wall-like structure built, e.g. around a fort, for defence; a rampart
a breakwater or seawall
a strong support or protection
Education is regarded as a bulwark of democracy
anything that acts as a defence
A pay rise of 30% would certainly be a bulwark against inflation
(usu in pl) the side of a ship above the upper deck
[Middle English bulwerke via early Dutch bolwerc from early High German, from bole plank + werc work]