underground

underground - English Dictionary

[ noun ]
■ an electric railway operating below the surface of the ground (usually in a city)
e.g.)
・in Paris the subway system is called the `metro' and in London it is called the `tube' or the `underground'
→ metro , subway , subway system , tube

[ noun ]
■ a secret group organized to overthrow a government or occupation force
→ resistance

[ adjective satellite ]
■ conducted with or marked by hidden aims or methods
e.g.)
・underground resistance
→ clandestine , cloak-and-dagger , hole-and-corner , hugger-mugger , hush-hush , secret , surreptitious , undercover

[ adjective satellite ]
■ under the level of the ground
e.g.)
・underground caverns
→ belowground

[ adverb ]
■ beneath the surface of the earth
e.g.)
・water flowing underground

[ adverb ]
■ in or into hiding or secret operation
e.g.)
・the organization was driven underground