Authority Bond

When a government issues a bond, it's usually backed by tax revenues. The government is borrowing money from the bond holders and will pay it back (with interest) using the taxes it collects from its citizens.
An authority bond is different. Instead of getting paid back with taxes, the authority bond is issued with some particular project in mind, and the borrowed money will be returned from revenue generated directly from that project.
For instance, a state might want to build a highway. It sets up a highway authority to conduct and oversee the project. In order to pay for the construction, the authority issues bonds, which are backed by revenues from toll booths that will be placed on the highway.
The bonds themselves can be issued by either a government or a corporation (there are some tax and other implications that can depend on exactly who and how the bonds are issued), but authority bonds always relate to some revenue-generating public work.