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English definition of “underground”


adjective, adverb (BELOW EARTH)    /ˌʌn.dəˈɡraʊnd/ US  /-dɚ-/
B2 below the surface of the Earth ; below ground : an underground cave / passage / cable Moles live underground.The Earth and outer space - general words
(Definition of underground adjectiveadverb (BELOW EARTH) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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