Webster’s Revised Unabridged Dictionary · 1913
Dioxide
Di·ox′ide, n. [Pref. di- + oxide.] (Chem.) (a) An oxide containing two atoms of oxygen in each molecule; binoxide. (b) An oxide containing but one atom or equivalent of oxygen to two of a metal; a suboxide. [Obs.]
Carbon dioxide. See Carbonic acid, under Carbonic.