accrual

Short definition from Wiktionary

Noun

1. 1
   The act or process of accruing; accumulation.
2. 2
   An increase; something that accumulates, especially an amount of money that periodically accumulates for a specific purpose
3. 3
   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.
4. 4
   Recruitment (of participants) to a clinical trial.