Synonyms: metro, tube, underground, subway, subway system
Definition: an electric railway operating below the surface of the ground (usually in a city)
Usage: in Paris the subway system is called the `metro' and in London it is called the `tube' or the `underground'
Similar words: railroad, railroad line, railway, railway line, railway system
Definition: line that is the commercial organization responsible for operating a system of transportation for trains that pull passengers or freight
Synonyms: resistance, underground
Definition: a secret group organized to overthrow a government or occupation force
Similar words: revolutionary group
Definition: a political unit organized to promote revolution
Synonyms: secret, undercover, underground, surreptitious, hole-and-corner, hugger-mugger, hush-hush, clandestine, cloak-and-dagger
Definition: conducted with or marked by hidden aims or methods
Usage: clandestine intelligence operations; cloak-and-dagger activities behind enemy lines; hole-and-corner intrigue; secret missions; a secret agent; secret sales of arms; surreptitious mobilization of troops; an undercover investigation; underground resistance
Similar words: covert
Definition: secret or hidden; not openly practiced or engaged in or shown or avowed
Usage: covert actions by the CIA; covert funding for the rebels
Synonyms: underground, belowground
Definition: under the level of the ground
Usage: belowground storage areas; underground caverns