nonvariable

Nonvariable refers to any quantity, symbol, or data item that remains unchanged under a specified context. In mathematics and modeling, nonvariables are usually constants or fixed parameters, contrasting with variables that can take different values.

In algebra, a constant is a nonvariable value that does not depend on the choice of the variable. For example, in the equation y = 3x + c, the numbers 3 and c are constants with respect to x.

In statistics and data analysis, a nonvariable parameter is assumed constant across observations, while variables may vary between units or over time. This distinction helps define models with fixed effects versus components that can change.

In computing, many programming languages treat certain values as nonvariables; constants are declared to prevent reassignment after initialization. Examples include const or final; some languages also allow compile-time constants for optimization.

Because usage varies by field, the term nonvariable is sometimes used interchangeably with constant or fixed parameter. When precision is important, it is better to use those established terms and specify the scope of constancy (with respect to which variables and over what domain).