subway subway /ˈsʌbˌweɪ/

noun

1. () [ N. American] An electric railway operating below the surface of the ground (usually in a city)  ( subway system [ N. American] , tube [UK] , underground [British] , metro , subway [ N. American] )
   an electric railway operating below the surface of the ground (usually in a city)
    In Paris the subway system is called the metro' and in London it is called the tube' or the underground'
   in Paris the subway system is called the metro' and in London it is called the tube' or the underground'
   
   
2. An underground tunnel or passage enabling pedestrians to cross a road or railway  ( subway , underpass )
   an underground tunnel or passage enabling pedestrians to cross a road or railway
    The underpass allows pedestrians to cross the busy road safely
   The underpass allows pedestrians to cross the busy road safely