/ Dictionary / Index O over-under: Meaning and Definition of Find definitions for: o•ver-un•der Pronunciation: (ō'vur-un'dur), [key] — adj. (of double-barreled firearms) with one barrel mounted over the other. —n. such a firearm. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. overturn overuse Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language