1. (

• profound ,
• unfathomed ,
• unplumbed ,
• unsounded

) 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" ;

2. (

• silent ,
• unsounded

) not made to sound; "the silent `h' at the beginning of `honor'"; "in French certain letters are often unsounded" ;