from the GNU version of the Collaborative International Dictionary of English
- adj. worked from the exposed surface; -- of mines and mining.
from The Century Dictionary and Cyclopedia
- In engineering, dug down from the surface; not tunneled; not covered during construction, as an underground railroad.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. (of mines and mining) worked from the exposed surface
Sorry, no etymologies found.