"To repay the principal" means to pay back the original amount of money that was borrowed or invested, without including any additional fees or interest. Full definition
Debt securities bought by retail investors do have repayment risk because their value is determined by the expectation that the issuer repay the principal at maturity. (retailinvestor.org)
Individual Bonds Bonds make interest payments and repay the principal on a fixed schedule. (fidelity.com)