outpost vs purlieu

outpost

noun
  • A square protected by a pawn that is in or near the enemy's stronghold. 

  • A military post stationed at a distance from the main body of troops. 

  • An outlying settlement. 

  • The body of troops manning such a post. 

purlieu

noun
  • The ground on the edges of a forest, especially when partly subject to the same forest laws concerning game hunting etc. 

  • The outskirts of any place; an adjacent district; the environs or neighborhood. 

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