un ‧ der ‧ pass /ˈʌndəpɑːs $ ˈʌndərpæs/ BrE AmE noun [countable] British English
[ Word Family: noun : ↑ pass , ↑ overpass ≠ ↑ underpass , ↑ passage , ↑ passing ; adjective : ↑ passing , ↑ passable ≠ ↑ impassable ; verb : ↑ pass ]
a road or path that goes under another road or a railway