A default on a loan or contract occurs when the borrower fails to meet the specifications of the contract, the legal duty required by the

To lend money at excessive interest rates.

A monetary part-payment as part of a staged payment plan. (source: http://en.wikipedia.org/wiki/Instalment)

Period of time specified in contract whereby the borrower of a loan would be exempted from interest payment of the principal.

Any of several parts into which a debt or other sum payable is divided for payment that creases at a geometric or arithmetic rate.

Any of several parts into which a debt or other sum payable is divided for payment at successive fixed times and amounts. (source: http://dictionary.reference.com/browse/instalment)