Definition

1. Noun:
   • A decisive test that produces a clear positive or negative result based on a single, crucial factor: A "litmus test" is a metaphor for a simple, definitive check used to make a judgment or classification. It originates from chemistry but is commonly used figuratively.
   • (Chemistry) A dye obtained from lichens used as an acid-base indicator: In its literal scientific sense, it is a coloring material that turns red in acidic conditions and blue in alkaline conditions, providing a basic test for pH.

Usage Examples

• Noun (Figurative):
  • For many voters, a candidate's position on healthcare is the litmus test.
  • His litmus test for a good restaurant is the quality of its bread.
• Noun (Literal/Chemistry):
  • We used litmus test paper to determine if the solution was acidic.
  • The classic litmus test involves dipping paper into a liquid to see if it turns red or blue.

Advanced Usage

• "To serve as a litmus test for": To function as the defining criterion for something.
  • Public reaction to the policy will serve as a litmus test for its future viability.
• "To apply a litmus test to": To judge or evaluate something using a single, decisive standard.
  • The committee applied a strict litmus test to all funding applications.

Variants and Related Words

• Litmus paper (n): Paper impregnated with litmus, used for quick acid-base tests.
  • The scientist tore off a strip of litmus paper.
• Litmus (n): The dye itself.
  • Litmus is derived from various lichen species.

Synonyms

• Benchmark: A standard or point of reference.
• Criterion: A principle or standard by which something is judged.
• Indicator: A thing that shows the state or level of something.
• Acid test: A conclusive test of value or quality (also derived from chemistry).

Related Idioms/Phrases

• "Pass/fail the litmus test": To meet or not meet the decisive standard.
  • The new design failed the boss's litmus test for simplicity.
• "The ultimate litmus test": The most important and definitive criterion.
  • Customer satisfaction is the ultimate litmus test for any business.

Noun

1. a test that relies on a single indicator
   • her litmus test for good breeding is whether you split infinitives
2. a coloring material (obtained from lichens) that turns red in acid solutions and blue in alkaline solutions; used as a very rough acid-base indicator