Oxford Advanced American Dictionary

Definition of subway noun from the Oxford Advanced Learner's Dictionary

subway

noun
subway pronunciation English ˈsʌbweɪ subway pronunciation American ˈsʌbweɪ
 
1 (North American English) an underground railway/railroad system in a citythe New York subwaya subway station/traina downtown subway stopto ride/take the subwayIn Boston the subway is known as the ‘T’; in Washington DC it's the‘Metro’.2 (British English) a path that goes under a road, etc. which people can use to cross to the other side
Synonym
underpass
Usage notesUsage note: underground / subway / metro / tubeA city’s underground railway/railroad system is usually called the underground (often the Underground) in British English and the subway in North American English. Speakers of British English also use subway for systems in American cities and metro for systems in other European countries. The Metro is the name for the systems in Paris and Washington, D.C. London’s system is often called the Tube.