noun a rapid transit system in an urban area, consisting of underground tunnels, elevated structures, and sometimes at-grade routes
noun a path for pedestrians alongside a road or street, typically paved or made of concrete
noun A path for pedestrians, usually paved or surfaced for easy walking
noun A rapid transit system, typically an underground or elevated railway system in a city
noun A combination of the words 'share' and 'arrow', used to indicate a lane on a road that is shared by both cyclists and motorists