Final answer:
The day a bond is paid-off is referred to as the maturity date, which is when the bond's principal and final interest payment are due to the investor.
Step-by-step explanation:
The day the bond is paid-off is best described by the maturity date. The maturity date is when the borrower, such as a corporation or government, repays the face value of the bond to the investor along with the last interest payment. Other terms related to bonds include the coupon rate, which is the interest rate paid on the bond, the par value or face value, which is the amount due at the maturity date, and the yield-to-maturity, which is the total return anticipated on a bond if it is held until it matures.