The correlation of longevity with validity of an idea or trend.

A Rorschach test

(chemistry) The addition of a single drop of a reagent to a small sample as a qualitative analytical test for the presence of a specific compound or class of compounds.

(statistics) A statistical test for deciding whether a data point is an outlier.

To test something using the conditions that it was designed to operate under, especially out in the real world instead of in a laboratory or workshop.

To fly an aircraft in order to evaluate its performance

To drive a motor vehicle in order to evaluate it, especially before potential purchase. / (by extension) To try out a product before committing to purchasing it.

Applied to premium gasoline. / (humorous, by extension) Of coffee: not decaffeinated. / Of a high standard.

(idiomatic) Alternative form of testbed

plural of litmus test