/ Dictionary / Index O ordinary differential equation: Meaning and Definition of Find definitions for: or'dinary differen'tial equa'tion Pronunciation: [key] an equation containing derivatives but not partial derivatives. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ordinary ordinary income Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language