from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Impenetrable by light: film stored in lightproof containers.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Sealed so that no light can enter.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. not penetrable by light
light + -proof (Wiktionary)