/ ˈbʊlwək; NAmE -wɜːrk/ noun
1.
bulwark (against sth) ( formal ) a person or thing that protects or defends sth :
a bulwark against communism
2.
a wall built as a defence
3.
[ usually pl. ] the part of a ship's side that is above the level of the deck
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WORD ORIGIN
late Middle English : from Middle Low German and Middle Dutch bolwerk ; related to bole and work .