| ̷ ̷ ̷ ̷(ˌ) ̷ ̷+...- noun
Etymology: indigodisulfonic International Scientific Vocabulary indigo + disulfonic
: a water-soluble disulfonic acid C 16 H 8 N 2 O 2 (SO 3 H) 2 obtained by treating indigo with concentrated sulfuric acid — called also indigo extract, 5,5′-indigotindisulfonic acid