Definition of: cycle

(sī′kəl) noun
1. Astron. a A period of time, at the end of which certain aspects or motions of the heavenly bodies repeat themselves. b An orbit or circle in the heavens.
2. A round of years or of ages; a vast period; eon.
3. Bot. An entire turn or circle, as of a spiral leaf-structure.
4. A body of legends, poems, or romances relating to one period, person, etc.; also, a series of miracle plays: the Chester cycle.
5. A bicycle, tricycle, etc.
6. Math. A closed path in a diagram; loop.
7. A series that repeats itself.
8. Physics A recurring series of operations, as in gas or other internal-combustion engines, in which heat is imparted to or taken from a substance, which by expansion or contraction gives out or stores up energy and is finally returned to its original condition.
9. Electr. A full period of an alternating current; also, a completed series of variations in electromagnetic waves of a given frequency, as in radio transmission.
—v.i. cy·cled, cy·cling
1. To pass through cycles.
2. To ride a bicycle, tricycle, or the like. [<F <LL cyclus <Gk. kyklos circle]