まずこいつ数学における定数も理解してないし。てか高校の数学の広い範囲で理解が怪しいっぽいな。

http://en.wikipedia.org/wiki/Constant_(mathematics)
>Constant (mathematics)
>In mathematics, a constant (more precisely, constant quantity) is a non-varying value, i.e.
>completely fixed or fixed in the context of use. The term usually occurs in opposition to
>variable (i.e. variable quantity), which is a symbol that stands for a value that may vary.

http://en.wikipedia.org/wiki/Constant_(programming)
>Constant (programming)
>In computer programming, a constant is a special kind of variable whose value cannot typically be
>altered by the program during its execution (though in some cases this can be circumvented,
>e.g. using self-modifying code). Many programming languages make an explicit syntactic distinction
>between constant and variable symbols.
>Although a constant's value is specified only once, a constant may be referenced many times in a
>program. Using a constant instead of specifying a value multiple times in the program can not only
>simplify code maintenance, but it can also supply a meaningful name for it and consolidate such
>constant bindings to a standard code location (for example, at the beginning).

http://dictionary.reference.com/browse/constant
> ？noun
> 7. something that does not or cannot change or vary.
> 8. Physics . a number expressing a property, quantity, or relation that remains unchanged under specified conditions.
> 9. Mathematics . a quantity assumed to be unchanged throughout a given discussion.

俺の好みは最後の" a quantity assumed to be unchanged throughout a given discussion."かな。
与えられた議論の中において不変であると理解される量。