/ Dictionary / Index T Three Mile Island: Meaning and Definition of Find definitions for: Three' Mile" Is'land Pronunciation: [key] an island in the Susquehanna River, near Middletown, Pennsylvania, SE of Harrisburg: scene of a near-disastrous accident at a nuclear plant in 1979 that raised the issue of nuclear-energy safety. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. three-master three-mile limit Related Content Daily Word Quiz: languid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language