/ Dictionary / Index A atomic hydrogen: Meaning and Definition of Find definitions for: atom'ic hy'drogen Pronunciation: [key] — Chem. Chem. hydrogen in the form of single atoms, rather than molecules, which makes it extremely reactive. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Atomic Energy Commission atomicity Related Content Daily Word Quiz: crutiny Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language