from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A decisive or critical test, as of worth or quality.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. a rigorous test or appraisal of the quality or worth of something
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a rigorous or crucial appraisal
From the testing of gold in nitric acid.(American Heritage® Dictionary of the English Language, Fourth Edition)
From the testing of gold with nitric acid (true gold is not affected) (Wiktionary)