/ Dictionary / Index H HO gauge: Meaning and Definition of Find definitions for: HO gauge Pronunciation: (āch'ō'), [key] a model railroad gauge of 5/8 in. (16 mm). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Hogarth chair hogback Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language