Acid Test

Also: Litmus test.

Used as an idiom since the 1900s.

Meaning of Acid Test Idiom

An acid test, when used as an idiom, is a situation or event that provides definitive proof of whether something is true or false, right or wrong, good or bad, effective or ineffective. This does not have to be an actual ‘test’ but can be anything which provides such conclusive confirmation. Quite often, the expression is used to refer to something which confirms a person’s character or ability.

The term is sometimes used more specifically in business as in the ‘acid test ratio’ which determines a business’ liquidity by examining its cash, accounts receivable, and trading securities.

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“He appears to be ready for management, but the acid test will be how he handles this production shortfall.”

“My knee has been fine in training but tomorrows game will be the acid test.”


The idiom acid test comes from tests used to check the fineness or purity of gold since gold is resistant to acid. This test figured prominently in the fortunes of the ’49’rs’ who flocked to the California Gold Rush of 1849, but the acid test didn’t enter the language as a common idiom until the 1900’s.

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