cycle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An interval of time during which a characteristic, often regularly repeated event or sequence of events occurs.
• noun A single complete execution of a periodically repeated phenomenon.
• noun A periodically repeated sequence of events.
• noun The orbit of a celestial body.
• noun A long period of time; an age.
• noun The aggregate of traditional poems or stories organized around a central theme or hero.
• noun A series of poems or songs on the same theme.
• noun A bicycle, motorcycle, or similar vehicle.
• noun Botany A circular or whorled arrangement of flower parts such as those of petals or sepals.
• noun Baseball The achievement of hitting a single, double, triple, and home run in a single game.
• intransitive verb To occur in or pass through a cycle.
• intransitive verb To move in or as if in a cycle.
• intransitive verb To ride a bicycle, motorcycle, or similar vehicle.
• intransitive verb To use in or put through a cycle.

from The Century Dictionary.

• To occur or recur in cycles.
• [See cycle, n., 9.] To ride or take exercise on a bicycle or tricycle.
• noun An imaginary circle or orbit in the heavens.
• noun A round of years or a recurring period of time used as a larger unit in reckoning time; especially, a period in which certain astronomical phenomena go through a series of changes which recur in the corresponding parts of the next period.
• noun Any long period of years; an age.
• noun Any round of operations or events; a series which returns upon itself; specifically, in physics, a series of operations by which a substance is finally brought back to the initial state.
• noun In literature, the aggregate of legendary or traditional matter accumulated round some mythical or heroic event or character, as the siege of Troy and the Argonautic expedition of antiquity, or the Round Table, the Cid, and the Nibelungs of medieval times, and embodied in epic or narrative poetry or in romantic prose narrative.
• noun In botany: In the theory of spiral leaf-arrangement, a complete turn of the spire which is assumed to exist.
• noun A closed circle or whorl of leaves.
• noun In corals, a set of septa of equal length. See septum.
• noun As used by the old medical sect of Methodists, an aggregate of curative means continued during a certain number of days, usually nine.
• noun A bicycle or tricycle; a “wheel.”
• noun In electricity, the time of one complete wave, or double reversal, of alternating currents. Frequencies are usually denoted in cycles per second. See alternating.
• noun In chem., same as ring, n. 18.
• noun In mech., a succession of conditions, operations, or phases which follow each other in a determinate order; specifically, in gas or internal-combustion motors, the successive changes experienced by the mixture of fuel and air in the motor cylinder.
• noun In mathematics: In geometry, a closed path in a multiply connected region.
• noun In function-theory, the set of homologous corners of a given region (in substitution-groups).
• noun In meteorology, the repetition of some general atmospheric phenomenon at approximately regular intervals.
• noun A false spelling of sickle. Fuller.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb To pass through a cycle{2} of changes; to recur in cycles.
• intransitive verb To ride a bicycle, tricycle, or other form of cycle.
• transitive verb To cause to pass through a cycle{2}.
• noun An imaginary circle or orbit in the heavens; one of the celestial spheres.
• noun An interval of time in which a certain succession of events or phenomena is completed, and then returns again and again, uniformly and continually in the same order; a periodical space of time marked by the recurrence of something peculiar.
• noun An age; a long period of time.
• noun obsolete An orderly list for a given time; a calendar.
• noun The circle of subjects connected with the exploits of the hero or heroes of some particular period which have served as a popular theme for poetry, as the legend of Arthur and the knights of the Round Table, and that of Charlemagne and his paladins.
• noun (Bot.) One entire round in a circle or a spire.
• noun A bicycle or tricycle, or other light velocipede.
• noun A motorcycle.
• noun (Thermodynamics) A series of operations in which heat is imparted to (or taken away from) a working substance which by its expansion gives up a part of its internal energy in the form of mechanical work (or being compressed increases its internal energy) and is again brought back to its original state.
• noun (Technology), (Elec.) A complete positive and negative, or forward and reverse, action of any periodic process, such as a vibration, an electric field oscillation, or a current alternation; one period.
• noun a period of 76 years, or four Metonic cycles; -- so called from Calippus, who proposed it as an improvement on the Metonic cycle.
• noun a period of about 6,586 days, the time of revolution of the moon's node; -- called Saros by the Chaldeans.