/ Dictionary / Index H high-energy physics: Meaning and Definition of Find definitions for: high'-en'er•gy phys'ics Pronunciation: (hī'en'ur-jē), [key] the branch of particle physics that deals with the collisions of particles accelerated to such high energies that new elementary particles are created by the collisions. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. High Energy Astrophysical Observatory higher apsis 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