Definition of "litmus test" []

• A test for chemical acidity or basicity using litmus paper. (noun)
• A test that uses a single indicator to prompt a decision: "The word 'hopefully' has become the litmus test to determine whether one is a language snob or a language slob” ( William Safire). (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.