Uumm, I think that they have it correct. I followed the link you gave (I use Wikipedia often) which went to a definition of Aircraft. I then followed their link to Autogyro and found the following definition the empahsis in bold is mine:
An autogyro (only an autogiro when produced by the Cierva Autogiro Company or one of its licensees (see below), sometimes called a gyroplane or Gyrocopter™) is an aircraft supported in flight by an unpowered rotary wing, or rotor.
Though the autogyro resembles a helicopter, it is driven in flight by an engine-powered propeller similar to that of an airplane. Though often mistakenly characterized as a hybrid between an airplane and helicopter, the autogyro is a distinct type of aircraft that made its first successful flight in 1923 at Cuatro Vientos Airfield in Madrid, Spain, predating the first successful helicopter by 13 years. All helicopters utilize rotor technology first developed for the autogiro: the helicopter owes its existence to the brilliant work conducted by Juan de la Cierva and his associates.
Found at this location:
Wikipedia they have a lengthy and (to the amateur reader) cogent explanation of how an autogyro works, it's strengths and limitations.