garrison vs parapet

garrison

noun
  • Occupants. 

  • The troops stationed at such a post. 

  • A permanent military post. 

  • A military unit, nominally headed by a colonel, equivalent to a USAF support wing, or an army regiment. 

verb
  • To convert into a military fort. 

  • To occupy with troops. 

  • To assign troops to a military post. 

parapet

noun
  • Hyponym: balustrade 

  • A fortification consisting of a wall. 

  • Part of a perimeter that extends above the roof. 

  • A low protective wall. 

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