U.S. TREASURY BILL: One kind of government security issued by the U. S. Treasury to obtain the funds used to finance the federal budget deficit. A Treasury bill (or T-bill) has a maturity length of one year or less, with 90 days a common maturity. T-bills, together with short-term commercial paper issued by businesses, are traded in money markets. The interest rate on T-bills is one of the key indicators of short-run economic activity. See also | government security | federal deficit | maturity | Treasury bond | Treasury note | commercial paper | money market | interest rate |