/ Dictionary / Index G gigaton: Meaning and Definition of Find definitions for: gi•ga•ton Pronunciation: (gig'u-tun", jig'-), [key] — n. one billion tons. Abbr.: GT Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Gigantopithecus* gigawatt Related Content Daily Word Quiz: portent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language