/ Dictionary / Index O opposeless: Meaning and Definition of Find definitions for: op•pose•less Pronunciation: (u-pōz'lis), [key] — adj. Archaic. tolerating no opposition or resistance; irresistible. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. opposed-piston engine opposite Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language