Underground ( adjective , noun )

(As an adjective)

Underground ( adjective )

1. Located beneath the surface of the ground.
2. Secret or hidden, often illegal or subversive.

Origin:

From middle english undergrund, undergroun, from old english undergrund ‎(“underground, subterranean, underworld”), equivalent to under- +‎ ground.

Examples:

1. The underground tunnels connect the buildings.
2. They have an underground bunker for emergencies.
3. The group operated an underground network to smuggle goods.
4. The book delves into the underground world of organized crime.
5. The artist gained a following in the underground music scene.

(As a noun)

Underground ( noun )

1. Located beneath the surface of the ground.
2. Secret or hidden, often illegal or subversive.

Origin:

From middle english undergrund, undergroun, from old english undergrund ‎(“underground, subterranean, underworld”), equivalent to under- +‎ ground.

Examples:

1. The underground tunnels connect the buildings.
2. They have an underground bunker for emergencies.
3. The group operated an underground network to smuggle goods.
4. The book delves into the underground world of organized crime.
5. The artist gained a following in the underground music scene.