Subway
1.
In
American
and
Canadian
English,
a
subway
is
a
mass
transit
system
with
trains
that
operate
underground;
also
known
as
a
metro
or
rapid
transit
system
(see
also
List
of
metro
systems);
also
known
as
the
underground
in
British
English,
e.g.
London
Underground.