-cycle is a suffix used in two contexts, transport and measurement.


The English suffix -cycle indicates a vehicle for transportation, but generally smaller than an automobile or truck. Alternatively, it is used to specify the number and arrangement of wheels in any vehicle. Typical is bicycle, a lightweight two wheel device powered by the rider, or a motorcycle, a two wheeled motor powered device substantially larger than a bicycle and which is not powered by the rider in normal operation. A unicycle is a one wheeled device, somewhat difficult to balance. A tricycle may refer to the wheel configuration of a vehicle of any size, including a prevalent aircraft landing gear configuration, or to a specific type of lightweight human powered vehicle. A quadracycle is usually a lightweight human powered or motor assisted pedaled vehicle.

(A motor assisted bicycle is called a moped. This word, like the device, being a combination of "motor" and "pedal".)


-cycle is also an indication of frequency of periodicity, usually associated with an additional modifier indicating the time unit. Typically used in units such as xxx kilocycles (thousand cycles) per second, xxx megacycles (million cycles) per second, etc., where xxx is some number. The cycles per second is often implicit such as in "this station broadcasts at 680 kilocycles" - this is taken to mean "680 kilocycles per second" or 680,000 cycles per second.

The "cycles per second" is now usually expressed with the unit "hertz", named in honor of the pioneering physicist Heinrich Rudolf Hertz and defined as "cycles per second". Thus 88 megacycles, or correctly, 88 megacycles per second, is now expressed as 88 megahertz.
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