from The American Heritage® Dictionary of the English Language, 4th Edition
- 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.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. tiredness or pain in the eyes, sometimes accompanied by headache, caused by excessive or improper use of the eyes, or by uncorrected defects of vision
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a tiredness of the eyes caused by prolonged close work by a person with an uncorrected vision problem
eye + strain (Wiktionary)