# Parameter

#### Pronunciation

*UK***IPA:***/pÉ™ËˆÉ¹Ã¦m.É™.tÉ™/*

#### Alternative forms

#### Origin

From *French* __paramÃ¨tre__, from *New Latin* __parametrum__ ("parameter"), from *Ancient Greek* __Ï€Î±ÏÎ¬__ ("beside") + __Î¼ÎÏ„ÏÎ¿Î½__ ("measure").

## Full definition of parameter

#### Noun

#### parameter

(*plural*)

**parameters**- (
*mathematics, physics*) A variable kept constant during an experiment, calculation or similar. - (
*programming*) An input variable of a procedure definition, that gets an actual value (argument) at execution time*(formal parameter)*.*Roughly, a tuple of arguments could be thought of as a vector, whereas a tuple of***parameters**could be thought of as a covector (i.e., linear functional). When a function is called, a**parameter**tuple becomes "bound" to an argument tuple, allowing the function instance itself to be computed to yield a return value. This would be roughly analogous to applying a covector to a vector (by taking their dot product (or, rather, matrix-product of row vector and column vector)) to obtain a scalar. - (
*programming*) An actual value given to such a formal parameter*(argument or actual parameter)*. - A characteristic or feature that distinguishes something from others.
- (
*geometry*) In the ellipse and hyperbola, a third proportional to any diameter and its conjugate, or in the parabola, to any abscissa and the corresponding ordinate.*The***parameter**of the principal axis of a conic section is called the latus rectum. - (
*crystallography*) The ratio of the three crystallographic axes which determines the position of any plane. - (
*crystallography*) The fundamental axial ratio for a given species.

#### Usage notes

(*the value used to instantiate the name*) Some authors regard use of *parameter* to mean *argument* as imprecise, preferring that *parameter* refers only to the name that will be instantiated, and *argument* to refer to the value that will be supplied to it at runtime.

#### Synonyms

- (
*value passed to a function*) argument - (
*characteristic distinguishing something from others*) distinguishing feature