A lender's guarantee on a specific interest rate
Until you request a rate lock, a loan's interest rate quoted by either a lender or broker is apt to change due to market fluctuations. The rules on how to do this will vary from lender to lender and broker to broker, but typically you can request a rate lock after you submit your signed loan application (1003) and other requested forms. Don't let a low rate slip through your fingers. Once you've settled on a rate, the lender usually guarantees the rate for 15, 30, 45 or 60 days. Rate lock is also called lock-in rate.
See: Lock period