Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun underground

2 senses of underground

Sense 1
underground, resistance -- (a secret group organized to overthrow a government or occupation force)
       => revolutionary group -- (a political unit organized to promote revolution)

Sense 2
metro, tube, underground, subway system, subway -- (an electric railway operating below the surface of the ground (usually in a city); "in Paris the subway system is called the `metro' and in London it is called the `tube' or the `underground'")
       => railway, railroad, railroad line, railway line, railway system -- (line that is the commercial organization responsible for operating a system of transportation for trains that pull passengers or freight)

Antonyms of adj underground

2 senses of underground

Sense 1
belowground, underground -- (under the level of the ground; "belowground storage areas"; "underground caverns")

INDIRECT (VIA surface, subsurface) -> overhead -- (located or originating from above; "an overhead crossing")
INDIRECT (VIA subsurface, overhead) -> surface -- (on the surface; "surface materials of the moon")

Sense 2
clandestine, cloak-and-dagger, hole-and-corner (prenominal), hugger-mugger, hush-hush, secret, surreptitious, undercover, underground -- (conducted with or marked by hidden aims or methods; "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")

INDIRECT (VIA covert) -> overt, open -- (open and observable; not secret or hidden; "an overt lie"; "overt hostility"; "overt intelligence gathering"; "open ballots")

Similarity of adj underground

2 senses of underground

Sense 1
belowground, underground -- (under the level of the ground; "belowground storage areas"; "underground caverns")
       => subsurface (vs. overhead) (vs. surface) -- (beneath the surface; "subsurface materials of the moon")

Sense 2
clandestine, cloak-and-dagger, hole-and-corner (prenominal), hugger-mugger, hush-hush, secret, surreptitious, undercover, underground -- (conducted with or marked by hidden aims or methods; "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")
       => covert (vs. overt) -- (secret or hidden; not openly practiced or engaged in or shown or avowed; "covert actions by the CIA"; "covert funding for the rebels")

Synonyms of adv underground

2 senses of underground

Sense 1
underground -- (in or into hiding or secret operation; "the organization was driven underground")

Sense 2
underground -- (beneath the surface of the earth; "water flowing underground")