nounThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A purification technique for crystalline substances in which a heating system passes slowly over a bar of the material to be refined, creating a molten region that carries impurities with it across the bar. Also called zone refining.