white-nose syndrome (w?t?n?z?, hw?t?-)n. An often fatal condition that affects hibernating bats and is characterized by white fungal growth especially on the muzzle and wing membranes.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.