parameter

A value kept constant during an experiment, equation, calculation or similar, but varied over other versions of the experiment, equation, calculation, etc.

A variable that describes some system (material, object, event etc.) or some aspect thereof

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."