Rate Lock ALL0-9ABCDEFGHIJKLMNOPQRSTUVWXYZ A commitment issued by a lender to a borrower or other mortgage originator guaranteeing a specified interest rate and lender costs for a specified period of time. Related Articles: New Construction & RenovationJoin GMMKristoffs at George Mason Mortgage - ConstructionKristoffs at George Mason Mortgage - Extended LocksKristoffs at George Mason Mortgage