Final answer:
A lock-in is a provision under which a lender guarantees a quoted interest rate for a specific period of time and prohibits any repayment of principal during that time.
Step-by-step explanation:
The provision described in the question is called a Lock-in. A lock-in is an arrangement between a borrower and a lender where the lender guarantees a quoted interest rate for a specific period of time. During this time period, the borrower is prohibited from repaying any principal on the loan.