[1] : WordNet (r) 2.0

underpass
     n : an underground tunnel or passage enabling pedestrians to
         cross a road or railway syn: subway
see also:
subway 

[2] : Moby Thesaurus II by Grady Ward, 1.0

37 moby thesaurus words for "underpass":
   access, aisle, alley, ambulatory, aperture, arcade, artery, avenue,
   channel, cloister, colonnade, communication, conduit, connection,
   corridor, covered way, defile, exit, ferry, ford, gallery, inlet,
   interchange, intersection, junction, lane, opening, outlet,
   overpass, pass, passage, passageway, portico, railroad tunnel,
   traject, trajet, tunnel

Underpass >> U Words
Underpass, definition of term: Underpass
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