Usury

n. lending of money at exorbitant interest rates

Usury (//, from the Medieval Latin usuria, "interest" or "excessive interest", from Latin usura "interest") was defined originally as charging a fee for the use of money. This usually meant interest on loans, although charging a fee for changing money (as at a bureau de change) is included in the original meaning. After moderate-interest loans were made more easily available usury became an accepted part of the business world in the early modern age. Today, the word has come to refer to the charging of unreasonable or relatively high rates of interest.
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Noun
1. an exorbitant or unlawful rate of interest
(synonym) vigorish
(hypernym) interest rate, rate of interest
2. the act of lending money at an exorbitant rate of interest
(hypernym) lending, loaning

(v. t.)
The practice of taking interest.
  

(v. t.)
Interest in excess of a legal rate charged to a borrower for the use of money.
  

(v. t.)
A premium or increase paid, or stipulated to be paid, for a loan, as of money; interest.
  

Excessive or illegal interest rate. - (read more on Usury)