›[Cusually singular]FINANCEan amount of money lent or borrowed, rather than the interest paid on it: She lives off the interest and tries to keep the principal intact.These bonds involve the risk that the issuing company may be unable to pay interest or repay principal.The money is secured by the borrower's home, which is sold after the borrower's death to pay off the interest and principal.
›[C]LAWa person who is directly involved in an arrangement, agreement, etc., rather than someone acting for that person: Once the principals sign the necessary papers the deal will be done.
›[C]LAWa person who has legal responsibility for what a business or organization does: I later became a principal at an investment banking firm.