constant

Con"stant , n. 1. (Astron.) A number whose value, when ascertained (as by observation) and substituted in a general mathematical formula expressing an astronomical law, completely determines that law and enables predictions to be made of its effect in particular cases.

2. (Physics) A number expressing some property or condition of a substance or of an instrument of precision; as, the dielectric constant of quartz; the collimation constant of a transit instrument.

Aberration constant, or Constant of aberration (Astron.), a number which by substitution in the general formula for aberration enables a prediction to be made of the effect of aberration on a star anywhere situated. Its value is 20″.47. -- Constant of integration (Math.), an undetermined constant added to every result of integration. -- Gravitation constant (Physics), the acceleration per unit of time produced by the attraction of a unit of mass at unit distance. When this is known the acceleration produced at any distance can be calculated. -- Solar constant (Astron.), the quantity of heat received by the earth from the sun in a unit of time. It is, on the C. G. S. system, 0.0417 small calories per square centimeter per second. Young.

Con"stant , n. 1. That which is not subject to change; that which is invariable.

2. (Math.) A quantity that does not change its value; -- used in countradistinction to variable.

Absolute constant (Math.), one whose value is absolutely the same under all circumstances, as the number 10, or any numeral. -- Arbitrary constant, an undetermined constant in a differential equation having the same value during all changes in the values of the variables.

Con"stant (?), a. [L. onstans, -antis, p. pr. of constare to stand firm, to be consistent; con- + stare to stand: cf. F. constant. See Stand and cf. Cost, v. t.]

1. Firm; solid; fixed; immovable; -- opposed to fluid. [Obs.]

If . . . you mix them, you may turn these two fluid liquors into a constant body.
Boyle.

2. Not liable, or given, to change; permanent; regular; continuous; continually recurring; steadfast; faithful; not fickle.

Both loving one fair maid, they yet remained constant friends.
Sir P. Sidney.

I am constant to my purposes.
Shak.

His gifts, his constant courtship, nothing gained.
Dryden.

Onward the constant current sweeps.
Longfellow.

3. (Math. & Physics) Remaining unchanged or invariable, as a quantity, force, law, etc. Contrasted with variable.

4. Consistent; logical. [Obs.] Shak.

Syn. -- Fixed; steadfast; unchanging; permanent; unalterable; immutable; invariable; perpetual; continual; resolute; firm; unshaken; determined. -- Constant, Continual, Perpetual. These words are sometimes used in an absolute and sometimes in a qualified sense. Constant denotes, in its absolute sense, unchangeably fixed; as, a constant mind or purpose. In its qualified sense, it marks something as a "standing" fact or occurence; as, liable to constant interruptions; constantly called for. Continual, in its absolute sense, coincides with continuous. See Continuous. In its qualified sense, it describes a thing as occuring in steady and rapid succession; as, a round of continual calls; continually changing. Perpetual denotes, in its absolute sense, what literally never ceases or comes to an end; as, perpetual motion. In its qualified sense, it is used hyperbolically, and denotes that which rarely ceases; as, perpetual disturbance; perpetual noise; perpetual intermeddling.