Entry 1 sense Webster, 1913 Superoxide /so͞opˌ-ẽr-äk'-sīdˌ/ · Su·per·ox·ide · IPA /sˌuːpərˈɑksˌaɪd/ 01 n. See Peroxide. 1. See Peroxide.(Chem.) [Obs.] See: Peroxide