1. A hard, dense, dark volcanic rock composed chiefly of plagioclase, pyroxene, and olivine, and often having a glassy appearance.
2. A kind of hard unglazed pottery.

[Latin basaltēs, alteration of basanītēs, touchstone, from Greek basanītēs (lithos), from basanos, of Egyptian origin.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.