# Constant

## Con"stant

, n. 1. That which is not subject to change; that which is invariable.
[1913 Webster]

2. (Math.) A quantity that does not change its value; -- used in countradistinction to variable.
[1913 Webster]

3. (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.
[Webster 1913 Suppl.]

4. (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.
[Webster 1913 Suppl.]

5. (Computers) a data structure that does not change during the course of execution of a program. It may be a number, a string, or a more complex data structure; -- contrasted with variable.
[PJC]

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. -- 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. -- 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. [Webster 1913 Suppl.] -- Constant of integration (Math.), an undetermined constant added to every result of integration.
[1913 Webster + Webster 1913 Suppl.]

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Mon 17th May 2021