Chronic inability to fall asleep or remain asleep for an adequate length of time.(noun)
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 "insomnia" in a sentence
"But my insomnia is like unto the Godzilla of insomnia."
"Thanks to the new (very expensive) medications, my insomnia is vastly better than it's been for years."
"The insomnia is back again tonight, and I cannot bear to just lie in bed, listening to Spooky sleep."