Entry 1 sense Webster, 1913 Acetic /(#; 277)/ · A·ce·tic · IPA /əˈsiːtɪk/ 01 a. Of a pertaining to vinegar; producing vinegar; producing vinegar; as, acetic fermentation. 1. Of a pertaining to vinegar; producing vinegar; producing vinegar; as, acetic fermentation.(Chem.)