“+...- noun
Etymology: International Scientific Vocabulary naphthylamine + sulfonic
: any of several amino sulfonic acids that are derived from the naphthylamines, have the properties of inner salts, and are used as dye intermediates: as
a. : brönner's acid
b. : cleve's acid
c. : laurent's acid
d. : naphthionic acid
e. : tobias acid