/ Dictionary / Index G GST: Meaning and Definition of Find definitions for: GST Pronunciation: [key] Greenwich Sidereal Time. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. GSR G star Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language