English

Noun

litmus test ‎(plural litmus tests)

1. (chemistry) A simple test for the acidity or alkalinity of a substance, using litmus paper.
2. (figuratively, by extension) Any test which produces a decisive result by measuring a single indicator.
   • 1940, Allison Danzig, "Leading Elevens Face Stern Threats in Saturday's Games," New York Times, 2 Oct., p. 27,

     Temple, under its new coach, Ray Morrison, formerly of Vanderbilt, will be put to the blue litmus test Friday night when it takes on Georgetown.

   • 1998, "Baby-Boomer Bonding," Newsweek, 16 Feb.,

     For good reasons or bad, early membership of the currency union has become the litmus test of being a "good European."

   • 2004, Matthew Cooper, "Candidates In the Wings," Time, 15 Nov.,

     He opposes a constitutional amendment to ban same-sex marriage—a litmus test for many social conservatives.

References

• "litmus test" at OneLook® Dictionary Search.
• Random House Webster's Unabridged Electronic Dictionary, 1987–1996.