from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Chronic inability to fall asleep or remain asleep for an adequate length of time.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A sleeping disorder that is known for its symptoms of unrest and the inability to sleep.
from the GNU version of the Collaborative International Dictionary of English
- n. Lack of sleep; inability to sleep, especially when chronic; wakefulness; sleeplessness.
from The Century Dictionary and Cyclopedia
- n. Sleeplessness; inability to sleep, especially when chronic.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an inability to sleep; chronic sleeplessness
Latin īnsomnia, from īnsomnis, sleepless : in-, not; see in-1 + somnus, sleep; see swep- in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin in- + somnus + -ia (Wiktionary)