noun
Used in finance for the original sum of money invested or loaned, excluding interest. Also used in business contexts for a person in a leading position, such as the head of a firm or a key party in a transaction.
投資のプリンシパルを守ることが最優先だ。
Protecting the principal of the investment is the top priority.
彼はその会社のプリンシパル
He participated in the negotiations as a principal of the company.