/ Dictionary / Index U underpass: Meaning and Definition of Find definitions for: un•der•pass Pronunciation: (un'dur-pas", -päs"), [key] — n. a passage running underneath, esp. a passage for pedestrians or vehicles, or both, crossing under a railroad, road, etc. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: underpass (Thesaurus) underpart underpay Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language