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

While campaigning against Clinton, Trump had positioned his victory as a litmus test for democracy.

From Los Angeles Times

Support of abortion bans as a litmus test for GOP politicians took some time to reach its full flowering.

From Los Angeles Times

This isn’t to say playing me bowling well is a litmus test for being a good batter, far from it.

From BBC

Where Schiff and Garvey stand on the Republican, who is again running for president, has repeatedly been used — including by the two campaigns — as a litmus test for their politics.

From Los Angeles Times

Still, the poll results will be seen as a litmus test ahead of Germany's federal elections in 2025.

From BBC