outpost vs supply depot

outpost

noun
  • The body of troops manning such a post. 

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

  • An outlying settlement. 

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

supply depot

noun
  • A facility utilized by armies to store battlefield supplies temporarily on or near the front lines until they can be distributed to army units. 

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