/ Dictionary / Index A adventitious: Meaning and Definition of Find definitions for: ad•ven•ti•tious Pronunciation: (ad"vun-tish'us), [key] — adj. associated with something by chance rather than as an integral part; extrinsic. appearing in an abnormal or unusual position or place, as a root. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: adventitious (Thesaurus) adventitia adventive Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language