/ Dictionary / Index H High Energy Astrophysical Observatory: Meaning and Definition of Find definitions for: High' En'ergy Astrophys'ical Observ'atory Pronunciation: [key] one of a series of three U.S. satellites launched (1977–79) into orbit around the earth and equipped with instruments for studying high-energy phenomena, as x-rays, gamma rays, and cosmic rays. Abbr.: HEAO Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. high-end high-energy physics Related Content Daily Word Quiz: pugilist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language