A Quick and Simple Dictionary

quadratic

1. Adjective.  square-shaped.
2. Adjective.  (mathematics) of a polynomial, involving the second power (square) of a variable but no higher powers, as $ax^2\; +\; bx\; +\; c$.
3. Adjective.  (mathematics) of an equation, of the form $ax^2\; +\; bx\; +\; c\; =\; 0$.
4. Adjective.  (mathematics) of a function, of the form $y\; =\; ax^2\; +\; bx\; +\; c$.
5. Noun.  (mathematics) A quadratic polynomial, function or equation.