Breadcrumb Home > Dictionary > Index O Cite OAO: Meaning and Definition of Find definitions for: OAO Pronunciation: [key] Orbiting Astronomical Observatory: one of a series of scientific satellites that studied astronomical phenomena at ultraviolet and x-ray wavelengths. Random House Unabridged Dictionary, Copyright 1997, by Random House, Inc., on Infoplease. O and O OAP TrendingHere are the facts and trivia that people are buzzing about. February 2021 Current Events: US News The Berlin Conference and the Partition of Africa The Implied Powers of Congress The Women's March on Versailles Keeping Your Brain Active in a COVID-19 World The Manchu Related Content Daily Word Quiz: suigeneris Analogy of the Day: Today?s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language