revolving credit

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Credit repeatedly available up to a specified amount as periodic repayments are made.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any form of credit that does not have a fixed number of payments

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a consumer credit line that can be used up to a certain limit or paid down at any time