The fee charged by a lender to a borrower for the use of borrowed money, usually expressed as an annual percentage of the principal; the

In the case of monthly payments, each payment covers principal repayment and interest for the month preceding the payment due date.

The annualized cost of credit or debt-capital computed as the percentage ratio of interest to the principal. (source: http://www.businessdictionary.com/definition/interest-rate.html#ixzz2ie9YRjeL)

The maximum interest rate that a financial institution can charge a borrower for an adjustable rate mortgage or loan according to the contractual terms of