2 synonym groups for Metro

subway, underground, tube, metro, rapid transit, urban train, city train, light rail, commuter train, mass [x]

metro, underground, tube, rapid transit, metro train, subway car, underground train, metro rail, urban train, city train, mass transit, light rail, commuter train, transit, rail transit, metro system, subway system, underground system, rapid rail, urban rail, city rail, transit system, metro service, subway service, underground service, rapid transit system, urban transit, city transit, mass transit system, light rail transit, commuter rail, transit network, metro network, subway network, underground network, rapid transit network, urban network, city network, mass transit network, light rail network, commuter network, transit line, metro line, subway line, underground line, rapid transit line, urban line, city line, mass transit line, light rail line [x]