Entry 1 sense Webster, 1913 oenothionic · oe·no·thi·on·ic · IPA 01 a. Pertaining to an acid now called sulphovinic acid or ethyl sulphuric acid. 1. Pertaining to an acid now called sulphovinic acid or ethyl sulphuric acid.(Chem.) Also: sulphovinic acid, ethyl sulphuric acid