bulwark
 oxford
 views  updated May 11 2018bul·wark  / ˈboŏlˌwərk/ •
n. a defensive wall. ∎ fig.  a person, institution, or principle that acts as a defense: the security forces are a bulwark against the breakdown of society.
 The Oxford Pocket Dictionary of Current English 
   bulwark
 oxford
 views  updated May 23 2018bulwark rampart, fortification XV; raised side of a ship XIX. immed. source doubtful, but prob. ult. a comp. of the words repr. by 
BOLE and 
WORK; cf. late MHG. 
bolwerk ballista, fortification.
  The Concise Oxford Dictionary of English Etymology T. F. HOAD
   Bulwark
 gale
 views  updated May 18 2018Bulwark
a collection of persons acting as a defense or safeguard to protect an ideal or way of life.
Examples: bulwark of Christendom, 1577; of our laws, 1614; of our liberties, 1789; to theology, 1837.
 Dictionary of Collective Nouns and Group Terms