The D.C. Court of Appeals ruled yesterday that mopeds are motor vehicles and fall within the scope of a District law that forbids the operation of a motor vehicle without the permission of its owner.

The appeals court reversed a D.C. Superior Court judge's ruling that the District's statute defining unauthorized use of a vehicle does not apply to mopeds.

Violation of the law in question constitutes a felony that carries a punishment of up to five years in jail and a $1,000 fine. It covers such vehicles as cars, mobile homes and motorcycles, but does not mention mopeds.

Earlier this year, D.C. Superior Court Judge Gladys Kessler held the mopeds are not covered by the law.

But the appeals court disagreed, asserting that the law's ban on the illegal use of motorcycles also applies to mopeds.

"We are . . . convinced that Congress intended that the term 'motorcycle' would be understood to mean any two-wheeled vehicle propelled by an internal combustion engine," Associate Judge Catherine B. Kelly held. Associate Judges Frank Q. Nebeker and Julia Cooper Mack concurred.

Mopeds are two-wheeled vehicles equipped with foot pedals and a small motor. Long popular in Europe, mopeds are now used widely in this country as a gasoline conservation measure.

Under District law, mopeds must be registered and drivers must have a motor vehicle operator's license or a special moped permit.