Metro is a rapid transit train system that run very often and carry many passengers at one time. It is usually in a city or urban area and takes people in and out of it. Unlike buses or trams, trains go between places very quickly because they do not mix with other traffic. Most rapid transit railways do not have level crossings, but the tracks go over and under other roads, or run in tunnels or over bridges, so they do not meet. Geography. Metro City (Indonesia), a city in Indonesia. A metropolitan area, the populated region including and surrounding an urban center. Public transport.
https://en.wikipedia.org/wiki/Metro