reimbursement vs repayment

reimbursement

noun
  • The act of compensating someone for an expense. 

repayment

noun
  • The act of repaying. 

  • The act of revenge, an act of revenge. 

  • The money or other item that is repaid. 

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