Experimentum crucis, meaning crucial experiment, refers to a scientific experiment that is designed to conclusively prove or disprove a hypothesis. Synonyms for this term include litmus test, acid test, decisive test, tipping point, and clincher. A litmus test is a quick and easy way to determine the acidic or basic nature of a substance. An acid test is a rigorous and demanding evaluation that is often used to identify the strength of a material. A decisive test is one that will determine the outcome of a particular experiment. A tipping point refers to the moment when an experiment reaches a critical juncture or turns in a specific direction. Finally, a clincher refers to a piece of evidence or data that provides the definitive answer to a scientific question.