unsounded in WordNet English dictionary

1. situated at or extending to great depth; too deep to have been sounded or plumbed
   "the profound depths of the sea"; "the dark unfathomed caves of ocean"-Thomas Gray; "unplumbed depths of the sea"; "remote and unsounded caverns"
   profound  unfathomed  unplumbed  unsounded 
   
2. not made to sound
   "the silent `h' at the beginning of `honor'"; "in French certain letters are often unsounded"
   silent  unsounded