Definition: A debenture is a bond issued with no collateral. Instead, investors rely upon the general creditworthiness and reputation of the issuing entity. If the issuer of a debenture were to default, investors would be placed at the level of general creditors in terms of their ability to recover funds from the issuer.
Debentures are normally only issued by the largest and most creditworthy of debt issuers, whose ability to repay is beyond question. These issuers use debentures in order to preserve their assets for use as collateral for more senior forms of debt. Further, they may see no need to use their assets as collateral, if investors are willing to pay sufficiently low interest rates for any debentures issued.
Both corporations and governments make use of debentures. Examples of debentures are Treasury bonds and Treasury bills.
A debenture is also known as an unsecured bond.