noun (n)

• a constant in the equation of a curve that can be varied to yield a family of similar curves(noun.cognition)

  Synonym:
  parametric quantity
  

  source: wordnet30
• any factor that defines a system and determines (or limits) its performance(noun.event)

  source: wordnet30
• (computer science) a reference or value that is passed to a function, procedure, subroutine, command, or program(noun.communication)

  Synonym:
  argument
  

  source: wordnet30
• a quantity (such as the mean or variance) that characterizes a statistical population and that can be estimated by calculations from sample data(noun.cognition)

  source: wordnet30
• A term applied to some characteristic magnitude whose value, invariable as long as one and the same function, curve, surface, etc., is considered, serves to distinguish that function, curve, surface, etc., from others of the same kind or family.(noun)

  source: webster1913