Index - the index is the measure of interest rate changes a lender uses to decide the amount an interest rate on an ARM will change over time; Reverse Mortgage rates are tied to the U.S. Treasury rates.

Initial interest rate - in the HECM program, the interest rate that is first charged on the loan beginning at closing; it equals the one-year rate for U.S. Treasury Securities, plus a margin.

Interest Rate Ceiling - for an adjustable-rate mortgage (ARM), the maximum interest rate as specified in the mortgage note.

Interest Rate Floor - for an adjustable-rate mortgage (ARM), the minimum interest rate as specified in the mortgage note.