from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A fine-grained, dark gray sedimentary rock, formed from silt and clay and similar to shale but without laminations.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A fine-grained sedimentary rock whose original constituents were clays or muds.
from The Century Dictionary and Cyclopedia
- n. A fine argillaceous rock, often containing more or less sand, somewhat harder than clay, and destitute of any distinct lamination.
Sorry, no etymologies found.