Impossible to slake or satisfy: unquenchable thirst. (adjective)
Impossible to suppress or destroy: unquenchable enthusiasm. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "unquenchable" in a sentence
"The information age equivalent of gold, the article asserts, is silicon -- and it calls the unquenchable search for success in the information age "siliconitis.""
"Actually, according to orthodox Christian dogma, eternal hell isn't just "separation from God," as in "Oh crap, God stuck me out here on this lonely planet where He never ventures," but literal torture in some kind of unquenchable inferno."
"They are known for their playfulness with language, love of long, sprawling sentences, and, above all, a kind of unquenchable honesty, a wrestling with memory and the world as it is."