battlement vs stockade

battlement

noun
  • In fortification: an indented parapet, formed by a series of rising members called cops or merlons, separated by openings called crenelles or embrasures, the soldier sheltering himself behind the merlon while he fires through the embrasure or through a loophole in the battlement. 

  • The towering roof of heaven. 

  • Any high wall for defense. 

stockade

noun
  • a military prison 

  • an enclosure protected by a wall of wooden posts 

verb
  • To enclose in a stockade. 

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