In the U.S., a vehicle as defined by Part 103 Section 103.1 of the FARs (Federal Aviation Regulations).
a lightweight aircraft subject to minimal regulation by the FAA (Federal Aviation Administration), the U
a vehicle that is manned by one occupant for recreation or sport purposes
a very small 'lawn mower' powered aircraft resembling a hang glider with a cockpit for two
A small, powered aircraft which is extremely light and seats only one or two occupants. Ultralights are popular among hobbyists for being cost-effective and having lenient regulation.
What we in the powered paragliding world fall under. Look up the FAA item...