underground meaning

EN[-aʊnd]

WUnderground

Underground most commonly refers to:
The regions beneath the surface of the Earth
Underground may also refer to:

NounPLundergroundsPREunder-
1. (chiefly Britain) An underground railway.
VerbSGundergroundsPRundergroundingPT, PPundergrounded
1. To route electricity distribution cables underground.
  1. One is to underground where no other alternative will work, and this method should be used universally in urban regions as it now is in “downtown” sections.
AdjectiveCOMmore undergroundSUPmost underground
1. (not comparable) Below the ground; below the surface of the Earth.
  1. There is an underground tunnel that takes you across the river. ‎
AdverbCOMmore undergroundSUPmost underground
1. Below the ground.
  1. The tunnel goes underground at this point.
More Examples
1. Used in the Middle of Sentence
  - The Ferranti effect is much more pronounced in underground cables, even in short lengths, because of their high capacitance.
2. Used in the Ending of Sentence
  - Note: In Britain, most cables are now located underground.

Meaning of underground for the defined word.

Grammatically, this word "underground" is an adjective. It's also an adverb. It's also a noun, more specifically, a countable noun. It's also a verb.

Part-of-Speech Hierarchy
1. Adjectives
2. Adverbs
3. Nouns
  - Countable nouns
4. Verbs

Difficultness: Level 2

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Easy ➨ Difficult

Definiteness: Level 9

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Definite ➨ Versatile