Definition of "Parameter" :

noun: a constant in the equation of a curve that can be varied to yield a family of similar curves

noun: a quantity (such as the mean or variance) that characterizes a statistical population and that can be estimated by calculations from sample data

noun: (computer science) a reference or value that is passed to a function, procedure, subroutine, command, or program

noun: any factor that defines a system and determines (or limits) its performance