from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Situated, occurring, or operating below the surface of the earth: underground caverns; underground missile sites.
- adj. Hidden or concealed; clandestine: underground resistance to the tyrant.
- adj. Of or relating to an organization involved in secret or illegal activity: underground trade in weapons.
- adj. Of or relating to an avant-garde movement or its films, publications, and art, usually privately produced and of special appeal and often concerned with social or artistic experiment.
- n. A clandestine, often nationalist, organization fostering or planning hostile activities against, or the overthrow of, a government in power, such as an occupying military government: "an underground of dissident intellectuals” ( Kenneth L. Woodward).
- n. Chiefly British A subway system.
- n. An avant-garde movement or publication.
- adv. Below the surface of the earth.
- adv. In secret; stealthily.
- transitive v. To situate under the ground: workers undergrounding telephone lines.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Below the ground; below the surface of the Earth.
- adj. Hidden, furtive, secretive.
- adj. Of music, art, etc, outside the mainstream.
- adv. Below the ground.
- adv. Secretly.
- n. An underground railway.
- n. A movement or organisation of people who resist political convention.
- n. A movement or organisation of people who resist artistic convention.
- v. To route electricity distribution cables underground
from the GNU version of the Collaborative International Dictionary of English
- prep. below the surface of the ground.
- n. The place or space beneath the surface of the ground; subterranean space.
- n. a subway or subway system, especially in the United Kingdom.
- n. a secret organization opposed to the prevailing government.
- n. a group or movement holding unorthodox views in an environment where conventional ideas dominate, as in artistic circles.
- adj. Being below the surface of the ground.
- adj. Done or occurring out of sight; secret.
- adv. Beneath the surface of the earth.
from The Century Dictionary and Cyclopedia
- n. An underground passage.
- n. A contraction of underground railway.
- Beneath the surface of the earth: as, to sink underground.
- Being below the surface of the ground: as, an underground story or apartment.
- n. That which is beneath the surface of the ground.
- To place or lay underground, as an electric wire.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. conducted with or marked by hidden aims or methods
- adv. in or into hiding or secret operation
- adv. beneath the surface of the earth
- adj. under the level of the ground
- n. an electric railway operating below the surface of the ground (usually in a city)
- n. a secret group organized to overthrow a government or occupation force
under + ground. (Wiktionary)