Entry 1 sense Webster, 1913 Isosulphocyanic · I·so·sul·pho·cy·an·ic · IPA 01 a. Pertaining to, or designating, an acid, HNCS, isomeric with sulphocyanic acid. 1. Pertaining to, or designating, an acid, HNCS, isomeric with sulphocyanic acid.(Chem.)