n. [ Pref. bi- + cycle. ] A light vehicle having two wheels one behind the other. It has a saddle seat and is propelled by the rider's feet acting on cranks or levers. [ 1913 Webster ]

n. One who rides a bicycle. [ 1913 Webster ]

[ After N. L. S. Carnot, French physicist. ] (Thermodynamics) An ideal heat-engine cycle in which the working fluid goes through the following four successive operations: (1) Isothermal expansion to a desired point; (2) adiabatic expansion to a desired point; (3) isothermal compression to such a point that (4) adiabatic compression brings it back to its initial state. [ Webster 1913 Suppl. ]

n. [ F. ycle, LL. cyclus, fr. Gr. ky`klos ring or circle, cycle; akin to Skr. cakra wheel, circle. See Wheel. ] 1. An imaginary circle or orbit in the heavens; one of the celestial spheres. Milton. [ 1913 Webster ]

2. 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; as, the cycle of the seasons, or of the year. [ 1913 Webster ]

Wages . . . bear a full proportion . . . to the medium of provision during the last bad cycle of twenty years. Burke. [ 1913 Webster ]

3. An age; a long period of time. [ 1913 Webster ]

Better fifty years of Europe than a cycle of Cathay. Tennyson. [ 1913 Webster ]

4. An orderly list for a given time; a calendar. [ Obs. ] [ 1913 Webster ]

We . . . present our gardeners with a complete cycle of what is requisite to be done throughout every month of the year. Evelyn. [ 1913 Webster ]

5. 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. [ 1913 Webster ]

6. (Bot.) One entire round in a circle or a spire; as, a cycle or set of leaves. Gray. [ 1913 Webster ]

7. A bicycle or tricycle, or other light velocipede. [ 1913 Webster ]

8. A motorcycle. [ PJC ]

9. (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. [ Webster 1913 Suppl. ]

10. (Technology) 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. Hence: (Elec.) A complete positive and negative wave of an alternating current. The number of cycles (per second) is a measure of the frequency of an alternating current. [ Webster 1913 Suppl. + PJC ]

Calippic cycle, a period of 76 years, or four Metonic cycles; -- so called from Calippus, who proposed it as an improvement on the Metonic cycle. --
Cycle of eclipses, a period of about 6, 586 days, the time of revolution of the moon's node; -- called Saros by the Chaldeans. --
Cycle of indiction, a period of 15 years, employed in Roman and ecclesiastical chronology, not founded on any astronomical period, but having reference to certain judicial acts which took place at stated epochs under the Greek emperors. --
Cycle of the moon, or
Metonic cycle, a period of 19 years, after the lapse of which the new and full moon returns to the same day of the year; -- so called from Meton, who first proposed it. --
Cycle of the sun,
Solar cycle, a period of 28 years, at the end of which time the days of the month return to the same days of the week. The dominical or Sunday letter follows the same order; hence the solar cycle is also called the cycle of the Sunday letter. In the Gregorian calendar the solar cycle is in general interrupted at the end of the century. [ 1913 Webster ]

v. i. [ imp. & p. p. Cycled. p. pr. & vb. n. Cycling ] 1. To pass through a cycle{ 2 } of changes; to recur in cycles. Tennyson. Darwin. [ 1913 Webster ]

2. To ride a bicycle, tricycle, or other form of cycle. [ 1913 Webster ]

v. t. To cause to pass through a cycle{ 2 }. [ PJC ]

n. [ L. epicyclus, Gr. &unr_;; 'epi` upon + &unr_; circle. See Cycle. ] 1. (Ptolemaic Astron.) A circle, whose center moves round in the circumference of a greater circle; or a small circle, whose center, being fixed in the deferent of a planet, is carried along with the deferent, and yet, by its own peculiar motion, carries the body of the planet fastened to it round its proper center. [ 1913 Webster ]

The schoolmen were like astronomers which did feign eccentrics, and epicycles, and such engines of orbs. Bacon. [ 1913 Webster ]

2. (Mech.) A circle which rolls on the circumference of another circle, either externally or internally. [ 1913 Webster ]

n. a stationary bike for exercising.
Syn. -- exercise bike, exercise bicycle. [ WordNet 1.5 ]

n. (Thermodynamics) A four-stroke cycle, as the Otto cycle, for an internal-combustion engine. -- Four"-cy`cle, a. [Webster 1913 Suppl.]

n. [ L. hemicyclus, Gr. &unr_;; &unr_; + ky`klos. ] 1. A half circle; a semicircle. [ 1913 Webster ]

2. A semicircular place, as a semicircular arena, or room, or part of a room. [ 1913 Webster ]

The collections will be displayed in the hemicycle of the central pavilion. London Academy. [ 1913 Webster ]

(Thermodynamics) The cycle for the air engine proposed by Joule. In it air is taken by a pump from a cold chamber and compressed adiabatically until its pressure is eqal to that of the air in a hot chamber, into which it is then delivered, thereby displacing an equal amount of hot air into the engine cylinder. Here it expands adiabatically to the temperature of the cold chamber into which it is finally exhausted. This cycle, reversed, is used in refrigerating machines. [ Webster 1913 Suppl. ]

v. i. to ride a motorcycle.
Syn. -- cycle. [ WordNet 1.5 ]

{ or }, n. A two-wheeled vehicle having a motor attached so as to be self-propelled. In common usage, a motorcycle is of heavier construction with larger wheels, a more powerful motor, and a higher maximum speed than a motorbike. A motorcycle may have a small appended compartment called a sidecar, supported by a third wheel, which can carry a passenger. [ Webster 1913 Suppl. ]

In Great Britain as of 1913 the term motor cycle was 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.). [ Webster 1913 Suppl. ]

(Thermodynamics) A four-stroke cycle for internal-combustion engines consisting of the following operations: First stroke, suction into cylinder of explosive charge, as of gas and air; second stroke, compression, ignition, and explosion of this charge; third stroke (the working stroke), expansion of the gases; fourth stroke, expulsion of the products of combustion from the cylinder. This is the cycle invented by Beau de Rochas in 1862 and applied by Dr. Otto in 1877 in the Otto-Crossley gas engine, the first commercially successful internal-combustion engine made. [ Webster 1913 Suppl. ]

. A bicycle with equal or nearly equal wheels, usually about 28 inches diameter, driven by pedals connected to the rear (driving) wheel by a multiplying gear. Since the 1930's this has been the most common type of bicycle, now simply called bicycle. The older high-wheelers are often referred to as bone-rattlers. [ Webster 1913 Suppl. +PJC ]

n. [ Pref. tri- + cycle as inbicycle. ] A three-wheeled velocipede. See Illust. under Velocipede. Cf. Bicycle. [ 1913 Webster ]

n. (Thermodynamics) A two-stroke cycle for an internal-combustion engine. -- Two"-cy`cle, a. [Webster 1913 Suppl.]