Situated, occurring, or operating below the surface of the earth, 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, Being below the surface of the ground, adverb_ Beneath the surface of the earth, Below the ground, in or into hiding or secret operation, noun_ a secret group organized to overthrow a government or occupation force, a group or movement holding unorthodox views in an environment where conventional ideas dominate, as in artistic circles, An underground passage, verb_ To route electricity distribution cables underground, transitive verb_ To situate under the ground