noun
- a severe and conclusive test to establish quality, genuineness, worth, etc.
noun
- a rigorous and conclusive test to establish worth or valuethe play passed the critic’s acid test
A decisive trial to determine worth or quality, as in Exposure to brilliant sunlight is the acid test for showing this fabric won’t fade. Alluding to a 19th-century chemical test for distinguishing gold from other metals, this term was used figuratively by the early 1900s.