A Debenture is a document that either creates a debt or acknowledges it, and it is without collateral. In corporate finance, this term is used for medium to long-term debt instrument used by large companies to borrow money. In some countries, the term is used interchangeably with bond, loan stock or note.
Debentures have no collateral. Bond buyers generally purchase debentures based on the belief that the bond issuer is unlikely to default on the repayment. An example of a government debenture would be any government-issued Treasury bond (T-bond) or Treasury bill (T-bill). T-bonds and T-bills are generally considered risk free because governments, at worst, can print off more money or raise taxes to pay these type of debts.