litmus test

noun

1. Chemistry.,  the use of litmus paper or solution to test the acidity or alkalinity of a solution.

2. a crucial and revealing test in which there is one decisive factor.

litmus test

noun

1. a test to establish the acidity or alkalinity of a mixture

2. a critical indication of future success or failure

Word History and Origins

Origin of litmus test¹

First recorded in 1955–60; so called from chemical tests in which litmus or litmus paper is an indicator

Example Sentences

The litmus tests for continuing negotiations over the summer was proof China was indeed allowing the flow of critical minerals.

Read more on Barron's

Bill Halldin, a spokesman for Bank of America, said “we serve more than 70 million clients, and we welcome conservatives. We never close accounts for political reasons and don’t have a political litmus test.”

Read more on The Wall Street Journal

With Week 1 as a litmus test, the dynamic looked much improved, thanks to another year of bonding with Johnston and Ladd McConkey and the added reliability of a returning Keenan Allen.

Read more on Los Angeles Times

The clearest emerging litmus test is opposition to sending offensive weapons, but other issues could loom large in Democratic primaries, including recognizing a Palestinian state and allowing international investigations of Israeli war crimes.

Read more on Salon

“It’s such an important litmus test for me. People would come over and be like, ‘uhh,’” she said of previous dates.

Read more on Los Angeles Times