Meaning

• 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."

• An actual value given to such a formal parameter (argument or actual parameter).

• A characteristic or feature that distinguishes something from others.

• 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."

• The ratio of the three crystallographic axes which determines the position of any plane.

• The fundamental axial ratio for a given species.