n.
Pain and fatigue of the eyes, often accompanied by headache, resulting from prolonged use of the eyes, uncorrected defects of vision, or an imbalance of the eye muscles.
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
