What is another word for mass rapid transit?
Pronunciation: [mˈas ɹˈapɪd tɹˈansɪt] (IPA) 
Mass Rapid Transit, or MRT, is a commonly used term to refer to urban rail systems that offer high-capacity transportation services to commuters. Some synonyms for MRT include "metro," "subway," "rapid transit," "underground," and "tube." Each of these terms refers to a comparable public transportation system that utilizes trains or light rail to move passengers quickly and efficiently through densely populated areas. Other terms that may be used interchangeably with MRT include "commuter rail," "heavy rail," and "urban rail," which are often used to describe the broader category of rail-based mass transit systems that serve a particular region or city.
