/ Dictionary / Index H hydrogen ion: Meaning and Definition of Find definitions for: hy'drogen i"on Pronunciation: [key] ionized hydrogen of the form H⫀, found in aqueous solutions of all acids. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. hydrogen iodide hydrogenize Related Content Daily Word Quiz: blanch Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language