Quick definitions from WordNet (unsounded)
▸ adjective: not made to sound ("In French certain letters are often unsounded")
▸ adjective: situated at or extending to great depth; too deep to have been sounded or plumbed ("Remote and unsounded caverns")
▸ adjective: not made to sound ("In French certain letters are often unsounded")
▸ adjective: situated at or extending to great depth; too deep to have been sounded or plumbed ("Remote and unsounded caverns")