from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A zone of the earth's mantle that lies beneath the lithosphere and consists of several hundred kilometers of deformable rock.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The zone of the Earth's upper mantle, below the lithosphere.
from the GNU version of the Collaborative International Dictionary of English
- n. the lower layer of the earth's crust, below the lithosphere. It is estimated as from fifty to several hundred miles thick. It is less rigid than the lithosphere, but still rigid enough to transmit some transverse seismic waves.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the lower layer of the crust
Greek asthenēs, weak; see asthenia + sphere.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Ancient Greek ἀσθενής ("weak") + sphere. (Wiktionary)