from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of unknown depth.
- adj. Not explored or unknown.
from The Century Dictionary and Cyclopedia
- Not fathomed or sounded; not to be sounded.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. situated at or extending to great depth; too deep to have been sounded or plumbed
un- + fathomed (Wiktionary)