a litmus test

litmus test

1. A chemical test used to determine acidity or alkalinity in a solution. The students performed a litmus test in class to learn whether the chemical solution was an acid or a base.
2. A test used to determine someone's true intentions or beliefs. I used his reaction to my favorite movie as a litmus test to determine if he was worth dating.
See also: litmus, test
Farlex Dictionary of Idioms.

a litmus test

JOURNALISM
COMMON If something is a litmus test of the quality or success of a particular thing, it is an effective way of proving it or measuring it. My personal litmus test when I have to decide whether to keep or discard something is whether or not I look at and enjoy it every day. The success of wind power represents a litmus test for renewable energy. Note: Litmus paper is used to test the acidity of substances. It turns red in acid conditions and blue in alkaline conditions.
See also: litmus, test
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • litmus
  • litmus test
  • test out
  • test for
  • test for (something)
  • the Bechdel test
  • bring (one) to the test
  • cram for a/the test
  • put somebody/something to the test
  • put to the test
References in periodicals archive
"The stakes are incredibly high and it will be a litmus test for us mentally.
"This is a litmus test. If these Tory MPs reject these principles and back a hard Brexit manifesto then people will know that on the biggest issue of the day they went missing in action."
The Savings-to-Employment Income Ratio is a litmus test for estimating the health of an investor's retirement savings and requires only a few pieces of information to calculate.
"The Dongria's campaign became a litmus test of whether a small marginalised tribe could stand up to a multinational company," Jo Woodman, a campaigner with the advocacy group Survival international, said in a statement.
It is a litmus test to see if this particular grouping of the western countries has moved towards honesty in the process of change, or not," Samareh Hashemi said in an interview with the Persian website, Parcham (Flag)."The talks have provided a golden and exceptional opportunity for the 5+1.
Perhaps nothing better exemplified the district than 7 World Trade Center, whose leasing success many considered a litmus test for the long-term prospects of the district and the need for the millions of squaree feet of new office space planned at the WTC site.
They can be someone to look up to and provide a litmus test: "What would so-and-so do in this situation?" For several of our interviewees, Martin Luther King was an inspirational mentor.
Catholic Senators Edward Kennedy, Joe Biden, Patrick Leahy, Richard Durbin, Chris Dodd and half a dozen others attacked the appointment with all their might trying to make the candidate's views on abortion a litmus test for rejection.
Making sex a litmus test of true communion owes more to Freud than to the Bible.
Appeals to voters should not be on the basis of religion, nor should a candidate's religious beliefs be a litmus test for public office."
veteran status is not a litmus test for a lawmaker's likely support for veterans issues," said National Legislative Director Joseph A.
"I believe [the senators] established a litmus test based on a difference of religious perspectives," Wilson said.
Such a litmus test may or may not be wrong, but there is nothing new about politicians opposing judicial nominees because of their positions on issues.
They had regarded the issue as a litmus test of Labour's policy on roadbuilding in Britain.
"Lincoln distinguished himself by publicly and repeatedly supporting the men and the dogs who were trying to capture the men, women and children who were trying to climb over the American Berlin Wall between slavery and [freedom in] Canada." Once he became president, Lincoln went a step further by making support for the law a litmus test for all potential cabinet appointees, Bennett writes.