/ Dictionary / Index O Orinoco: Meaning and Definition of Find definitions for: O•ri•no•co Pronunciation: (ôr"u-nō'kō, ōr"- Sp. ô"rē-nô'kô), [key] — n. a river in N South America, flowing N from the border of Brazil, along the E border of Colombia, and NE through Venezuela to the Atlantic. 1600 mi. (2575 km) long. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: orinoco (Thesaurus) O-ring oriole Related Content Daily Word Quiz: opulent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language