lith·arge (l?th?ärj?, l?-thärj?)n. A yellow lead oxide, PbO, used in storage batteries and glass and as a pigment. Also called lead monoxide, massicot.[Middle English litarge, from Old French, alteration of litargire, from Latin lithargyrus, from Greek litharguros : lithos, stone + arguros, silver (from the production of litharge as a byproduct of the extraction of silver from argentiferous galena); see arg- in Indo-European roots.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.litharge (?l????d?) n (Elements & Compounds) another name for lead monoxide[C14: via Old French from Latin lithargyrus, from Greek, from lithos stone + arguros silver]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014lith?arge (?l?? ?rd?, l????rd?) n. a yellowish or reddish poisonous solid, PbO, used chiefly in the manufacture of storage batteries. [1350?1400; litarge