accrual vs depletion

accrual

noun
  • from the creditor's viewpoint, a charge incurred in one accounting period that has not been, but is to be, paid by the end of it. 

  • An increase; something that accumulates, especially an amount of money that periodically accumulates for a specific purpose 

depletion

noun
  • The consumption of a resource faster than it can be replenished. 

  • gradual expense or use of natural resources over time. 

  • The act of depleting, or the state of being depleted; exhaustion. 

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