oil shale

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A black or dark brown shale containing hydrocarbons that yield petroleum by distillation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a dark-brown or black shale, from which petroleum-like hydrocarbons can be produced by distillation

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun shale from which oil can be obtained by heating