noun A value kept constant during an experiment, equation, calculation, or similar, but varied over other versions of the experiment, equation, calculation, etc.
noun A variable that describes a property or characteristic of some system (material, object, event, etc.) or some aspect thereof.
noun Any measured quantity of a statistical population that summarises or describes an aspect of the population.
noun A variable of a model that is trained by a machine learning algorithm.
noun An input variable of a function definition, that gets an actual value (argument) at execution time.
noun An actual value given to such a formal parameter.
noun A characteristic or feature that distinguishes something from others.
noun 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.