1. A wall or embankment raised as a defensive fortification; a rampart.
2. Something serving as a defense or safeguard: "We have seen the necessity of the Union, as our bulwark against foreign danger" (James Madison).
3. A breakwater.
4. The part of a ship's side that is above the upper deck. Often used in the plural.

1. To fortify with a wall, embankment, or rampart.
2. To provide defense or protection for.

Synonyms: These nouns refer literally to structures used as a defense against attack. A bulwark can be a mound of earth, an embankment, or a wall-like fortification. Barricade usually implies hasty construction to meet an imminent threat. Breastwork denotes a low defensive wall, especially a temporary one hurriedly built. Earthwork is a defensive construction of earth. A rampart, the main defensive structure around a guarded place, is permanent, high, and broad. A bastion is a projecting section of a fortification from which defenders have a wide range of view and fire. Parapet applies to any low fortification, typically a wall atop a rampart. Of these words bulwark and bastion are the most frequently used to refer figuratively to something regarded as being a safeguard or a source of protection: "The only sure bulwark of continuing liberty is a government strong enough to protect the interests of the people, and a people strong enough and well enough informed to maintain its sovereign control over its government" (Franklin D. Roosevelt). A free press is one of the bastions of a democracy.