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subterranean, subterraneous, underground, subterrene | being or operating under the surface of the earth | |
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subway, metro, tube, underground, subway system, métro, underground railway, el/El, Tube | an electric railway operating below the surface of the ground (usually in a city) | |
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resistance, underground | a secret group organized to overthrow a government or occupation force | |
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underground | in or into hiding or secret operation | |
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underground, belowground | under the level of the ground | |
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secret, clandestine, undercover, cloak-and-dagger, hole-and-corner, hugger-mugger, hush-hush, surreptitious, underground, hidden | conducted with or marked by hidden aims or methods | |
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underground | beneath the surface of the earth |