Definitions of derivative:

• noun:   (linguistics) a word that is derived from another word

  Example: "`electricity' is a derivative of `electric'"

• noun:   the result of mathematical differentiation; the instantaneous change of one quantity relative to another; df(x)/dx
• noun:   a financial instrument whose value is based on another security
• adjective:   resulting from or employing derivation

  Example: "A derivative process"