Source : Webster's Revised Unabridged Dictionary (1913)

Bulwark \Bul"wark\, n. [Akin to D. bolwerk, G. bollwerk, Sw.
   bolwerk, Dan. bolv["a]rk, bulv["a]rk, rampart; akin to G.
   bohle plank, and werk work, defense. See {Bole} stem, and
   {Work}, n., and cf. {Boulevard}.]
   1. (Fort.) A rampart; a fortification; a bastion or outwork.

   2. That which secures against an enemy, or defends from
      attack; any means of defense or protection.

            The royal navy of England hath ever been its
            greatest defense, . . . the floating bulwark of our
            island.                               --Blackstone.

   3. pl. (Naut.) The sides of a ship above the upper deck.

   Syn: See {Rampart}.

Bulwark \Bul"wark\, v. t. [imp. & p. p. {Bulwarked}; p. pr. &
   vb.n. {Bulwarking}.]
   To fortify with, or as with, a rampart or wall; to secure by
   fortification; to protect.

         Of some proud city, bulwarked round and armed With
         rising towers.                           --Glover.

Source : WordNet®

bulwark
     v : defend with a bulwark

bulwark
     n 1: 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" [syn: {rampart},
           {wall}]
     2: a fence-like structure around a deck [syn: {bulwarks}]
     3: a protective structure of stone or concrete; extends from
        shore into the water to prevent a beach from washing away
        [syn: {breakwater}, {groin}, {groyne}, {mole}, {seawall},
        {jetty}]