Implicit-function meaning

A function whose value can only be computed indirectly from one or more of the independent variables. For example, in the equation x² + y² = 1, y is an implicit function of x.

The mathematical rule or function which permits computation of one variable directly from another when an equation relating both variables is given (Ex.: y is an implicit function of x in the equation x + y³ + 2x²y + xy = 0)