litmus test

Merriam-Webster's Word of the Day for May 17, 2013 is: litmus test • \LIT-mus-TEST\  • noun : a test in which a single factor (as an attitude, event, or fact) is decisive Examples: For Curtis, the litmus test of good barbeque ribs is whether or not they have that moist fall-off-the-bone quality. "The students who are following the discussion often look uncomfortable at this point, and the moment serves as a litmus test to see who really is paying attention." - From an article by Dolores T. Puterbaugh in USA Today, November 2012 Did you know? It was in the 14th century that scientists discovered that litmus, a mixture of colored organic compounds obtained from lichen, turns red in acid solutions and blue in alkaline solutions and, thus, can be used as an acid-base indicator. Six centuries later, people began using "litmus test" figuratively. It can now refer to any single factor that establishes the true character of something or causes it to be assigned to one category or another. Often it refers to something (such as an opinion about a political or moral issue) that can be used to make a judgment about whether someone or something is acceptable or not. See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.