Fixed interest securities issued by the government. They may be in the nature of bonds or other types of security and may or may not be redeemable. They may be issued to banks and other institutions in the money market or to the general public through banks or the post office. The treasury bill is a specific type of government security which is issued only within the money market, and particularly to discount houses, which tender for these bills each week. The rate of dis3unt at which they are allotted is a pointer to the general health of the economy and can influence the current minimum lending rate.
Reference: The Penguin Business Dictionary, 3rd edt.