noun

1. Math. a quantity or constant whose value varies with the circumstances of its application, as the radius line of a group of concentric circles, which varies with the circle under consideration
2. any constant, with variable values, used as a referent for determining other variables
3. : usage objected to by some
   1. a boundary or limit
   2. a factor or characteristic: usually used in pl.

Etymology: ModL parametrum < Gr para-, para- + metron, measure