Meaning of UNDERGROUND in English

UNDERGROUND

n.

Pronunciation: ' ə n-d ə r- ˌ grau ̇ nd

Function: adjective

Date: 1601

1 : being, growing, operating, or situated below the surface of the ground

2 : conducted by secret means

3 a : existing outside the establishment <an underground literary reputation> b : existing outside the purview of tax collectors or statisticians <the underground economy>

4 a : produced or published outside the establishment especially by the avant-garde < underground movies> < underground newspapers> b : of or relating to the avant-garde underground <an underground moviemaker> <an underground theater>

Merriam Webster Collegiate English Dictionary.      Merriam Webster - Энциклопедический словарь английского языка.