/ Dictionary / Index O Oto: Meaning and Definition of Find definitions for: O•to Pronunciation: (ō'tō), [key] — pl. O•tos, O•to. a member of a Siouan-speaking tribe of North American Indians who formerly inhabited the lower Missouri River basin and now live in Oklahoma. oto- Pronunciation: [key] a combining form meaning “ear,” used in the formation of compound words: otology. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: oto (Thesaurus) otium cum dignitate* otocyst Related Content Daily Word Quiz: belligerent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language