constant

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. ]

n. a copper-nickel alloy composed of approximately 55 per cent copper and 45 per cent nickel, with high electrical resistance and a low temperature coefficient; it is used as resistance wire and in thermocouples. It has a resistance factor ρ of 44.1 x 10-6 ohm-cm at 0° C, in comparison to the value 1.71 x 10-6 ohm-cm for pure copper and 7.8 x 10-6 ohm-cm for pure nickel. It is similar to the alloy Eureka, which has a ρ = 47 x 10-6 ohm-cm. Handbook of Ch. 61. [ WordNet 1.5 +PJC ]

n. A superior wine, white and red, from Constantia, in South Africa. [ 1913 Webster +PJC ]

prop. n. the former capital of the Eastern Roman Empire; it was built on the site of ancient Byzantium, and the name was changed to Istanbul by the Turks.
Syn. -- Istanbul, Stambul, Stamboul. [ WordNet 1.5 ]

The name change was the subject of a humorous song in the 1950's "Istanbul (not Constantinople)":

 Artists: The Four Lads -- peak Billboard position # 10 in 1953 -- Words by Jimmy Kennedy and Music by Nat Simon -- (C) Chappell & Co. Istanbul was Constantinople Now it's Istanbul, not Constantinople Been a long time gone, Constantinople Now it's Turkish delight on a moonlit night Every gal in Constantinople Lives in Istanbul, not Constantinople So if you've a date in Constantinople She'll be waiting in Istanbul Even old New York Was once New Amsterdam Why they changed it I can't say People just liked it better that way Take me back to Constantinople No, you can't go back to Constantinople Now it's Istanbul, not Constantinople Why did Constantinople get the works? That's nobody's business but the Turks'