stockpile vs supply depot

stockpile

noun
  • A supply (especially a large one) of something kept for future use, specifically in case the cost of the item increases or if there a shortage. 

  • A supply of nuclear weapons kept by a country; a nuclear stockpile. 

  • A pile of coal or ore heaped up on the ground after it has been mined. 

verb
  • To accumulate or build up a supply of (something). 

  • To build up a stock of (nuclear weapons). 

  • To heap up piles of (coal or ore) on the ground after it has been mined. 

  • To build up a supply; to accumulate. 

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 stockpile and supply depot occurred in a corpus of books? (source: Google Ngram Viewer )