|e]thē]|änik-, |ē], ]ˌthī]\ noun
Etymology: ethionic International Scientific Vocabulary e- (from ether ) + -thion- (from Greek theion brimstone) + -ic — more at thi-
: an unstable diacid HO 3 SCH 2 CH 2 OSO 3 H known only in solution and obtainable by adding water to ethionic anhydride