conserve vs deplete

conserve

verb
  • To protect an environment, heritage, etc. 

  • To remain unchanged during a process 

  • To save for later use, sometimes by the use of a preservative. 

noun
  • Wilderness where human development is prohibited. 

  • A jam or thick syrup made from fruit. 

deplete

verb
  • To empty or unload, as the vessels of the human system, by bloodletting or by medicine. 

  • To reduce by destroying or consuming the vital powers of; to exhaust, as a country of its strength or resources, a treasury of money, etc. 

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