Synonyms of the word

subway

• n. (Canada, US, Scotland) An underground railway, especially for mass transit of people in urban areas.
• n. (US) A rapid transit system, regardless of the elevation of its right of way.
• n. (Britain) An underground walkway, tunnel for pedestrians (called pedestrian underpass in US).
• v. (intransitive, US, informal) To travel by underground railway.

metro

• n. An underground railway.
• n. A train that runs on such an underground railway.
• n. An urban rapid transit light railway.
• n. A train that runs on such a railway.
• n. A metropolitan area.
• adj. Metropolitan.

railroad

• n. (chiefly US and Canada) A permanent road consisting of fixed metal rails to drive trains or similar motorized…
• n. (chiefly US and Canada) The transportation system comprising such roads and vehicles fitted to travel…
• n. (chiefly US and Canada) A single, privately or publicly owned property comprising one or more such roads…
• n. (figuratively) A procedure conducted in haste without due consideration.
• v. (transitive) To transport via railroad.
• v. (intransitive) To operate a railroad.
• v. (intransitive) To work for a railroad.
• v. (intransitive) To travel by railroad.
• v. (intransitive) To engage in a hobby pertaining to railroads.
• v. (transitive) To manipulate and hasten a procedure, as of formal approval of a law or resolution.
• v. (transitive) To convict of a crime by circumventing due process.
• v. (transitive) To procedurally bully someone into an unfair agreement.
• v. (role-playing games) To force characters to complete a task before allowing the plot to continue.
• v. (upholstery) To run fabric horizontally instead of the usual vertically.

railway

• n. (chiefly Britain, Ireland and Commonwealth of Nations) A transport system using rails used to move passengers…
• n. (chiefly Britain, Ireland and Commonwealth of Nations) A track, consisting of parallel rails, over which…

tube

• n. Anything that is hollow and cylindrical in shape.
• n. An approximately cylindrical container, usually with a crimped end and a screw top, used to contain and…
• n. (Britain, colloquial, often capitalized as Tube) The London Underground railway system, originally referred…
• n. (Australia, slang) A tin can containing beer (or other beverage?).
• n. (surfing) A wave which pitches forward when breaking, creating a hollow space inside.
• n. (Canada, US, colloquial) A television. Also, derisively, boob tube. British: telly.
• v. To make or use tubes.

tunnel

• n. An underground or underwater passage.
• n. A passage through or under some obstacle.
• n. A hole in the ground made by an animal, a burrow.
• n. (computing, networking) A wrapper for a protocol that cannot otherwise be used because it is unsupported,…
• n. A vessel with a broad mouth at one end, a pipe or tube at the other, for conveying liquor, fluids, etc…
• n. The opening of a chimney for the passage of smoke; a flue.
• n. (mining) A level passage driven across the measures, or at right angles to veins which it is desired to…
• v. (transitive) To make a tunnel through or under something, to burrow.
• v. (intransitive) To make a tunnel.

underground

• adj. (not comparable) Below the ground; below the surface of the Earth.
• adj. Hidden, furtive, secretive.
• adj. Of music, art, etc, outside the mainstream.
• adv. Below the ground.
• adv. Secretly.
• n. (chiefly Britain) An underground railway.
• n. (with "the") A movement or organisation of people who resist political convention.
• n. (with "the") A movement or organisation of people who resist artistic convention.
• v. To route electricity distribution cables underground.

underpass

• n. A road or a pedestrian passage in a tunnel that runs underneath a road or railroad.