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Principal, in the context of debt financing, is the initial amount of money that is borrowed in a loan. [...] For example, if you borrow $100,000 for a real estate investment, the principal is $100,000. At a 5% interest rate, that’s equal to about $5,000 per year in interest. (Realized1031.com)

The loan amounts outstanding totaled about $32.2 million in principal and $2.2 million in interest. (Longman Business Dictionary)

Willis North America intends to use the net proceeds of the Offering to (i) repay approximately $175 million principal amount under its term loan facility and related accrued interest, which will result in a payment in full of the term loan facility and termination of the term loan credit agreement and related loan documents [...] (CNN Business)

The amount of interest you pay on a loan is determined by the principal amount. The larger the principal, the higher your interest payments will be. (Investopedia)