What does the word underground mean?

Usage examples for underground

  1. I have been too long underground, because, while I continue to hide, I am as a drawn sword between two lovers." – The Complete Project Gutenberg Works of George Meredith by George Meredith
  2. Sometimes he wondered if the members of his underground- or anybody else for that matter- ever realized the grim conclusions formed by the Philosophy of Violence. – Rastignac the Devil by Philip José Farmer
  3. The psychological effect was that of blank darkness, the black darkness of far underground, although the moon was sailing the heavens. – The Killer by Stewart Edward White