Gilsonite definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
Origin: after S. H. Gilson, of Salt Lake City, Utah
Gilsonite definition by American Heritage Dictionary
A trademark used for a natural black bitumen employed in the manufacture of acid, alkali, and waterproof coatings.