bulwark

Etymology

Comes from Middle English bulwerk, from Middle Dutch bolwerk, bolwerc and Middle Low German bolwerk, equivalent to bole ("tree trunk") plus work. It is cognate with German Bollwerk, Danish bolværk, Swedish bålverk and Dutch bolwerk, and is a doublet of boulevard (from French boulevard, from Dutch); it is also cognate with Portuguese and Spanish baluarte and Italian baluardo.