bulwark

Etymology

From Middle English bulwerk, from Middle Dutch bolwerk, bolwerc and Middle Low German bolwerk, equivalent to bole (“tree trunk”) + work. Cognate with German Bollwerk, Danish bolværk, Swedish bålverk, Dutch bolwerk. Doublet of boulevard (from French boulevard, from Dutch); cognate with Portuguese and Spanish baluarte and Italian baluardo.

noun

1. A defensive wall or rampart.
2. A defense or safeguard.
3. A breakwater.
4. (nautical) The planking or plating along the sides of a nautical vessel above her gunwale that reduces the likelihood of seas washing over the gunwales and people being washed overboard.
5. (figurative) Any means of defence or security.

verb

1. (transitive) To fortify something with a wall or rampart.
2. (transitive) To provide protection of defense for something.