[adv., uhn-der-ground; adj., n., v. uhn-der-ground] 
| 1. | beneath the surface of the ground: traveling underground by subway. |
| 2. | in concealment or secrecy; not openly: subversion carried on underground. |
| 3. | existing, situated, operating, or taking place beneath the surface of the ground. |
| 4. | used, or for use, underground. |
| 5. | hidden or secret; not open: underground political activities. |
| 6. | published or produced by political or social radicals or nonconformists: an underground newspaper. |
| 7. | avant-garde; experimental: an underground movie. |
| 8. | critical of or attacking the established society or system: underground opinion. |
| 9. | of or for nonconformists; unusual: an underground vegetarian restaurant. |
| 10. | the place or region beneath the surface of the ground. |
| 11. | an underground space or passage. |
| 12. | a secret organization fighting the established government or occupation forces: He fought in the French underground during the Nazi occupation of France. |
| 13. | (often initial capital letter ) a movement or group existing outside the establishment and usually reflecting unorthodox, avant-garde, or radical views. |
| 14. | Chiefly British. a subway system. |
| 15. | to place beneath the surface of the ground: to underground utility lines. |
[suhb-wey] | 1. | Also called, especially British, tube, underground. an underground electric railroad, usually in a large city. |
| 2. | Chiefly British. a short tunnel or underground passageway for pedestrians, automobiles, etc.; underpass. |
| 3. | to be transported by a subway: We subwayed uptown. |