New Age vs underground

New Age

noun
  • A modern spiritual and religious movement. 

adj
  • Of or relating to a broad movement in Western culture, covering a wide variety of alternative spiritual and philosophical ideas, often spirituality, mysticism, holism, and environmentalism, and partially based on eastern religions such as Buddhism and Hinduism, that developed towards the end of the 20th century. 

  • Of or relating to New Age music. 

underground

noun
  • A movement or organisation of people who resist political convention. 

  • A movement or organisation of people who resist artistic convention. 

  • Regions beneath the surface of the earth, both natural (eg. caves) and man-made (eg. mines). 

  • Synonym of subway: a railway that is under the ground. 

adj
  • Hidden, furtive, secretive. 

  • Below the ground; below the surface of the Earth. 

  • Outside the mainstream, especially unofficial and hidden from the authorities. 

verb
  • To route electricity distribution cables underground. 

adv
  • Below the ground. 

  • Secretly. 

How often have the words New Age and underground occurred in a corpus of books? (source: Google Ngram Viewer )