/ Dictionary / Index I IGY: Meaning and Definition of Find definitions for: IGY Pronunciation: [key] International Geophysical Year. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Iguassú Falls I-head engine Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language