/ Dictionary / Index O operational calculus: Meaning and Definition of Find definitions for: opera'tional cal'culus Pronunciation: [key] — Math. Math. a method for solving a differential equation by treating differential operators as ordinary algebraic quantities, thus obtaining a simpler problem. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. operational amplifier operationalism Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language