/ Dictionary / Index O oncornavirus: Meaning and Definition of Find definitions for: on•cor•na•vi•rus Pronunciation: (ong-kôr'nu-vī"rus, -kôr"nu-vī'-), [key] — pl. -rus•es. any of various RNA viruses that cause tumors in humans and other animals. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. oncoming ondine Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language