acetate Syllabification: (ac·e·tate)Pronunciation: /ˈasiˌtāt/Translate acetate | into Italian Definition of acetate noun 1 Chemistry a salt or ester of acetic acid, containing the anion CH3COO or the group OOCCH3. 2cellulose acetate, especially as used to make textile fibers or plastic: [as modifier]:acetate silk a transparency made of cellulose acetate film. a recording disk coated with cellulose acetate. Origin: late 18th century: from acetic + -ate1acetate in other Oxford dictionaries Definition of acetate in the British & World English dictionary