/ Dictionary / Index S Simplon: Meaning and Definition of Find definitions for: Sim•plon Pronunciation: (sim'plon Fr. san&sylpplôn'), [key] — n. a mountain pass in S Switzerland, in the Lepontine Alps: crossed by a carriage road constructed 1800–06 on Napoleon's orders. 6592 ft. (2010 m) high. a tunnel between Switzerland and Italy, NE of the Simplon Pass: longest tunnel in the world. 12 mi. (20 km) long. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. simplistic simply Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language