Meaning of UNDERGROUND in English

UNDERGROUND

I. ˌən-dər-ˈgrau̇nd adverb

Date: 14th century

1. : beneath the surface of the earth

2. : in or into hiding or secret operation

II. ˈən-dər-ˌgrau̇nd noun

Date: 1594

1. : a subterranean space or channel

2. : an underground city railway system

3.

a. : a movement or group organized in strict secrecy among citizens especially in an occupied country for maintaining communications, popular solidarity, and concerted resistive action pending liberation

b. : a clandestine conspiratorial organization set up for revolutionary or other disruptive purposes especially against a civil order

c. : an unofficial, unsanctioned, or illegal but informal movement or group ; especially : a usually avant-garde group or movement that functions outside the establishment

III. ˈən-dər-ˌgrau̇nd 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's Collegiate English vocabulary.      Энциклопедический словарь английского языка Merriam Webster.