/ Dictionary / Index F first derivative: Meaning and Definition of Find definitions for: first' deriv'ative Pronunciation: [key] — Math. Math. the derivative of a function:Cf. second derivative. Velocity is the first derivative of distance with respect to time. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. first-degree murder first division Related Content Daily Word Quiz: nefarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language