We call an instrument of the U.S. Treasury with a maturity less than or equal to one year--we call that a bill and they used to be the only discount bonds issued by the U.S. Government.

我们把期限小于或等于一年的,国库券品种称为短期国库券,它们曾是美国政府,唯一发行的贴现债券

耶鲁公开课 - 金融市场课程节选