A space or area below the surface of the ground, often used for storage, transportation, or habitation. The underground was cool and damp compared to the scorching heat above.
A secret or hidden organization or movement, especially one that is involved in political resistance or illegal activities. The underground worked tirelessly to distribute pamphlets and organize protests against the oppressive regime.
A genre of music or culture that is outside the mainstream, often characterized by its alternative or non-commercial nature. The band's sound was heavily influenced by the underground music scene of the 1980s.
A subway system, particularly in the United Kingdom. We took the underground to get to the museum quickly and avoid traffic.