The term 'rate per cent' simply refers to the percentage that is paid or gained on a particular investment or loan. Some synonyms for this term include interest rate, annual percentage rate (APR), finance charge, and annualized rate of return. The interest rate is the most common synonym since it's the amount paid to a lender or earned on an investment over a period of time. APR, on the other hand, includes other costs of a loan, such as fees or charges. Finance charge is also used to represent the cost of borrowing money, while the annualized rate of return is often used as a measure of the performance of an investment.