Protoxide
Pronunciation : Pro*tox"ide
Part of Speech : n.
Etymology : [Proto- + oxide: cf. F. protoxide.] (Chem.)
Definition : Defn: That one of a series of oxides having the lowest proportion of oxygen. See Proto-, 2 (b). protoxide of nitrogen, laughing gas, now called hyponitrous oxideNO. See under Laughing.
Source : Webster's Unabridged Dictionary, 1913