litmus test

• Test ou indicateur décisif qui révèle la nature véritable, la qualité ou l'acceptabilité de quelque chose, souvent utilisé dans les contextes de prise de décision ou d'évaluation.

A decisive test or indicator that reveals the true nature, quality, or acceptability of something, often used in decision-making or evaluation contexts.

1. Decisive indicatorB2formal

   A situation or event that reveals the true character or nature of something or someone.

   Test décisif / pierre de touche

   • The election was a litmus test for the new policy.
   • His reaction to the crisis was a litmus test of his leadership.
   • This project will be a litmus test for our team's capabilities.

2. Chemical testB2formal

   A test using litmus paper to determine if a substance is acidic or basic.

   test au tournesol

   • The litmus test turned red, indicating the solution was acidic.
   • In chemistry class, we performed a litmus test on various liquids.
   • A blue litmus test turning red shows the presence of an acid.