Under both types of loan, the principal sum immediately reduces every time a loan instalment is made.

在这两类贷款中，每一次缴付贷款分期付款，本金数额将会随之减少。

youdao

Interest on time deposits is payable only at maturity of the deposit period, when it will be credited to the principal sum in the absence of instructions to the contrary.

定期存款的利息只可在存款期满时支付，而在没有相反指示之情况下，将会在存款期满时纳入本金。

youdao

A note calling for periodic payments which are insufficient to fully amortize the face amount of the note prior to maturity, so that a principal sum known as a "balloon" is due at maturity.

一种周期性付款到期前不足摊还面额的贷款，所以称作“气球”的本金额到期时需要一次付清。

youdao

We should be assigned a health savings account at birth, whose principal sum would grow over the years and need not be expended by a particular date.

FORBES: Obama Care's Assault on Dr. Carson's Health Savings Accounts (and My Tax Bill)

The accounts in Swiss banks will be taxed at between 19% and 34% by the Swiss authorities on the principal sum, depending on how long the account has been running.

BBC: MEPs: Investigate UK-Swiss tax agreement

Debts are often best tackled by paying off the principal lump sum.

BBC: Why banks are likely to face more software glitches in 2013