6-month Libor

What it means: Libor stands for London Interbank Offered Rate. It's the rate of interest at which banks offer to lend money to one another in the wholesale money markets in London. It is a standard financial index used in U.S. capital markets and can be found in The Wall Street Journal. In general, its changes have been smaller than changes in the prime rate.

How it's used: It's an index that is used to set the cost of various variable-rate loans. Lenders use such an index, which varies, to adjust interest rates as economic conditions change. They then add a certain number of percentage points called a margin, which doesn't vary, to the index to establish the interest rate you must pay. When this index goes up, interest rates on any loans tied to it also go up. Although it is increasingly used for consumer loans, it has traditionally been a reference figure for corporate financial transactions.