adjective satellite (s)

• situated at or extending to great depth; too deep to have been sounded or plumbed(adj.all)

  Example:
  Remote and unsounded caverns.
  

  Synonym:
  profound, unfathomed, unplumbed
  

  source: wordnet30
• not made to sound(adj.all)

  Example:
  In French certain letters are often unsounded.
  

  Synonym:
  silent
  

  source: wordnet30