- s situated at or extending to great depth; too deep to have been sounded or plumbed
the dark unfathomed caves of ocean"-Thomas Gray
- For many reasons, the sea floor remains an unfathomed, and largely unfathomable, mystery.
- The President might even be involved, if only at third hand, in the still unfathomed life and times of Boston Operator Bernard Goldfine, the man that Sherman Adams vouches for.
- The biochemistry of the vast majoritymillionsof other species is an unfathomed reservoir of new and potentially more effective substances.