Is it ensure, insure, or assure?
derivative de·riv·a·tive (dĭ-rĭv'ə-tĭv)
Something obtained or produced by modification of something else.
A chemical compound that may be produced from another compound of similar structure in one or more steps.
In calculus, the slope of the tangent line to a curve at a particular point on the curve. Since a curve represents a function, its derivative can also be thought of as the rate of change of the corresponding function at the given point. Derivatives are computed using differentiation.