brön·ner's acid noun orbroen·ner's acid\ˈbrenə(r)z-, -rən-, -rə̄n-\ Usage: usually capitalized B Etymology: probably from the name Brönner : a colorless crystalline naphthylaminesulfonic acid NH2C10H6SO3H used as a dye intermediate; 6-amino-2-naphthalenesulfonic acid