T-Bill
Treasury Bill — a short-term debt security issued by the U.S. government, maturing in a year or less (common terms are 4, 8, 13, 26, and 52 weeks). T-Bills are sold at a discount to their face value and pay no separate interest; the investor's return is the difference between the purchase price and the amount paid at maturity. They're widely considered one of the safest investments available, backed by the full faith and credit of the U.S. government.