Parameter

noun

1. A value kept constant during an experiment, equation, calculation or similar, but varied over other versions of the experiment, equation, calculation, etc.
2. A variable that describes some system (material, object, event etc.) or some aspect thereof
3. 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."

4. An actual value given to such a formal parameter (argument or actual parameter).
5. A characteristic or feature that distinguishes something from others.