Englishfor English speakers
underground
Adjective
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of or about being under the ground
Underground water is drying up.
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secret or not well known
The underground music scene is really interesting.
Underground drug sales have increased over the last year.
underground
Preposition
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being or moving under the ground
Let's go underground. It's safer down there.
The new trains will run underground.
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If you go underground, you keep your activities secret.
underground
Noun
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The underground is a system of trains that runs mostly under the ground.
The London underground is a great way to move about the city.
gasification
—
noun
the process of changing into gas
coal gas is produced by the gasification of coal