• located or occurring below the surface of the earth
    1. underground parking garages
    2. an underground explosion
  • secret and usually illegal
    1. an underground deal
    2. The drugs are supplied through an underground network.
  • of, relating to, or produced in a social and artistic world that is different and separate from the main part of society
    1. She loves the city's underground music scene.
    2. underground newspapers/movies
  • below the surface of the earth
    1. The wires run underground.
    2. animals that live underground
  • in or into a place that is hidden or secret
    1. They had been living underground as fugitives.
    2. The political party went underground [=started working in secret] after the new government took power.
  • Noun
  • a system of trains that run below the ground in a large city
    1. I've ridden on the New York subway, the Paris Metro, and the London Underground.
    2. She commutes by underground.
  • a group of people who secretly work to oppose or overthrow a government