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Underground

/ˈʌndəɡɹaʊnd/

An underground railway, especially for mass transit of people in urban areas.

Full Dictionary Entry

📖 Definitions of "Underground"

noun

1
An underground railway, especially for mass transit of people in urban areas.
2
A train that runs on such an underground railway.
3
A rapid transit system, regardless of the elevation of its right of way.
4
An underground walkway, tunnel for pedestrians (called pedestrian underpass in US).

noun

1
Regions beneath the surface of the earth, both natural (eg. caves) and man-made (eg. mines).
2
(with definite article) A movement or organisation of people who resist political convention.
"the French underground during World War II"
3
(with definite article) A movement or organisation of people who resist artistic convention.

verb

1
To route electricity distribution cables underground

adjective

1
Below the ground; below the surface of the Earth.
"There is an underground tunnel that takes you across the river."
2
Hidden, furtive, secretive.
"These criminals operate through an underground network."
3
Outside the mainstream, especially unofficial and hidden from the authorities.
"underground music"

🔄 Synonyms of "Underground"

21 synonyms found via WordNet and Google Books.

Word	Definition
surreptitious	Stealthy, furtive, well hidden, covert (especially movements).
clandestine	Done or kept in secret, sometimes to conceal an illicit or improper purpose.
partisannoun	A fervent, sometimes militant, supporter or proponent of a party, cause, faction, person, or idea.
secretnoun	(countable) A piece of knowledge that is hidden and intended to be kept hidden.
irregularnoun	Nonstandard; not conforming to rules or expectations.
resistancenoun	The act of resisting, or the capacity to resist.
cloak-and-dagger	Marked by menacing furtive secrecy, often with a melodramatic tint or espionage involved.
guerrillanoun	A soldier in a small independent group, fighting against the government or regular forces by surprise raids.
hugger-muggernoun	Secret, clandestine, sly.
partizannoun	Alternative spelling of partisan (“adherent, supporter”). [An adherent to a party or faction.]
tubenoun	Anything that is hollow and cylindrical in shape.
undercovernoun	Performed or happening in secret.
belowground	Beneath the surface of the ground; underground.
hush-hushnoun	Secret, not spoken of (or spoken of only in hushed whispers between insiders).
subsurfacenoun	Something that is below the layer that is on the surface.
guerillanoun	Obsolete spelling of guerrilla, now a misspelling. [A soldier in a small independent group, fighting against the government or regular forces by surprise raids.]
hole-and-corner	Conducted in secret; clandestine.
on the quiet	(informal) surreptitiously
subwaynoun	(Canada, US, Scotland, South Africa) An underground railway, especially for mass transit of people in urban areas.
covertnoun	(figuratively) Secret, surreptitious, concealed.
metronoun	(general) A rapid transit rail transport system, or a train in such systems, generally underground and serving a metropolitan area.

💡 Words with a Similar Meaning to "Underground"

Found via reverse dictionary — words that share a conceptual meaning.

Word	Definition
belowgroundnoun	Beneath the surface of the ground; underground.
subsurfacenoun	Something that is below the layer that is on the surface.
metronoun	(general) A rapid transit rail transport system, or a train in such systems, generally underground and serving a metropolitan area.
subwaynoun	(Canada, US, Scotland, South Africa) An underground railway, especially for mass transit of people in urban areas.
tubenoun	Anything that is hollow and cylindrical in shape.
guerillanoun	Obsolete spelling of guerrilla, now a misspelling. [A soldier in a small independent group, fighting against the government or regular forces by surprise raids.]
guerrillanoun	A soldier in a small independent group, fighting against the government or regular forces by surprise raids.
covertnoun	(figuratively) Secret, surreptitious, concealed.
undercovernoun	Performed or happening in secret.
cloak-and-dagger	Marked by menacing furtive secrecy, often with a melodramatic tint or espionage involved.
hugger-muggernoun	Secret, clandestine, sly.
surreptitious	Stealthy, furtive, well hidden, covert (especially movements).
hole-and-corner	Conducted in secret; clandestine.
clandestine	Done or kept in secret, sometimes to conceal an illicit or improper purpose.
hush-hushnoun	Secret, not spoken of (or spoken of only in hushed whispers between insiders).
secretnoun	(countable) A piece of knowledge that is hidden and intended to be kept hidden.
on the quiet	(informal) surreptitiously
partisannoun	A fervent, sometimes militant, supporter or proponent of a party, cause, faction, person, or idea.
partizannoun	Alternative spelling of partisan (“adherent, supporter”). [An adherent to a party or faction.]
resistancenoun	The act of resisting, or the capacity to resist.