bulwark vs entanglement

bulwark

noun
  • A defensive wall or rampart. 

  • A defense or safeguard. 

  • A breakwater. 

  • Any means of defence or security. 

  • 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. 

verb
  • To fortify something with a wall or rampart. 

  • To provide protection of defense for something. 

entanglement

noun
  • An obstruction placed in front or on the flank of a fortification, to impede an enemy's approach. 

  • An obstruction of cables and spars across a river or harbour entrance. 

  • The condition of being deeply involved and intricated (with politics, a group, another person, etc.) 

  • The condition, or an instance, of being romantically or sexually involved with another person; an affair. 

  • The act of entangling. 

How often have the words bulwark and entanglement occurred in a corpus of books? (source: Google Ngram Viewer )