underground

Meanings

• a secret group organized to overthrow a government or occupation force
• an electric railway operating below the surface of the ground (usually in a city)
  • "in Paris the subway system is called the `metro' and in London it is called the `tube' or the `underground'"
• under the level of the ground
  • "underground caverns"
• conducted with or marked by hidden aims or methods
  • "underground resistance"
• in or into hiding or secret operation
  • "the organization was driven underground"
• beneath the surface of the earth
  • "water flowing underground"

Synonyms

belowground, clandestine, cloak-and-dagger, hole-and-corner, hugger-mugger, hush-hush, metro, resistance, secret, subway, subway system, surreptitious, tube, undercover