2.TTRBritish EnglishBrE a path for people to walk under a road or railway 〔公路或铁路下的〕地下通道,地下人行道SYN underpass
nTHESAURUS
the subwayAmerican EnglishAmE the railway system that runs under the ground below a big city. British people use the underground when talking about the railway system in London, and many systems outside the US
the New York subway
We got on the next subway train.
the undergroundBritish EnglishBrE the railway system that runs under the ground below a big city
the London underground
an underground map
It’s quickest to travel by underground.
the tubeBritish EnglishBrE informal the railway system that runs under London
We took the tube to Trafalgar Square.
a crowded tube train
the metro used especially to talk about the railway system that runs under Paris. Also used about some other city’s systems, for example Moscow, Washington DC and Newcastle