Added 9 October 2026 dioxide /daɪˈɒksaɪd/ noun Categories: NatureUncommon Words noun ! Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about dioxide at Wordnik → Where our words come from → Any oxide containing two oxygen atoms in each molecule. Related Words: monoxideoxidetrioxidesulfuranhydridesulphuraceticcarbonanhydritegasiceso2 Back to today's word