odd function definition
Definition of Odd Function. The function f(x) is said to be 'odd' if and only if f(x) is a real-valued function of a real variable x, and f(- x) = - f(x).1  The graph of an odd function is symmetric with respect to the origin.he function f(x) is said to be 'odd' if and only if f(x) is a real-valued function of a real variable x, and f(- x) = - f(x). 1  The graph of an odd function is symmetric with respect to the origin.