I. ˈsəbˌwā noun
Etymology: sub- + way
1. : an underground way or gallery: as
a. : a passage under a street (as for pedestrians, electric cables, water mains)
b. : a usually electric railway built partly or entirely underground and usually for local transit in metropolitan areas
c. : underpass
2. : a subway train
the subway pounds along over a steel viaduct — Blake Ehrlich
II. intransitive verb
( -ed/-ing/-s )
: to travel by subway