Motor cycle \Motor cycle\, or Motorcycle \Mo"tor*cy`cle\, n. A bicycle having a motor attached so as to be self-propelled. In Great Britain the term motor cycle is treated by statute (--3 Ed VII. c. 36) as limited to motor cars (self-propelled vehicles) designed to travel on not more than three wheels, and weighing unladen (that is, without water, fuel, or accumulators necessary for propulsion) not more than three hundred weight (336 lbs.).

Source: Webster's Revised Unabridged Dictionary (1913)