Meaning of the word "acid test" in English

What does "acid test" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

acid test

US /ˈæsɪd test/
UK /ˈæsɪd test/
"acid test" picture

Idiom

a conclusive test of the effectiveness or value of something

Example:
The real acid test will be how the new policy performs in practice.
Winning this championship was the acid test for the team's new strategy.