Washington

Motorcycle:

“a motor vehicle designed to travel on not more than three wheels, not including any stabilizing conversion kits, on which the driver: (1) Rides on a seat or saddle and the motor vehicle is designed to be steered with a handlebar; or (2) Rides on a seat in a partially or completely enclosed seating area that is equipped with safety belts and the motor vehicle is designed to be steered with a steering wheel. ‘Motorcycle’ excludes a farm tractor, a power wheelchair, an electric personal assistive mobility device, a motorized foot scooter, an electric-assisted bicycle, and a moped.”

Motor-Driven Cycle:

“every motorcycle, including every motor scooter, with a motor that produces not to exceed five brake horsepower (developed by a prime mover, as measured by a brake applied to the driving shaft). A motor-driven cycle does not include a moped, a power wheelchair, a motorized foot scooter, or an
electric personal assistive mobility device.”

Moped:

“a motorized device designed to travel with not more than three wheels in
contact with the ground and having an electric or a liquid fuel motor with a
cylinder displacement not exceeding fifty cubic centimeters which produces no more than two gross brake horsepower (developed by a prime mover, as
measured by a brake applied to the driving shaft) that is capable of propelling the device at not more than thirty miles per hour on level ground.”