/ Dictionary / Index H HST: Meaning and Definition of Find definitions for: HST Pronunciation: [key] Hawaii Standard Time. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. H.S.M. H-stretcher Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language