'Protoxide' definitions:
Definition of 'Protoxide'
From: GCIDE
- Protoxide \Pro*tox"ide\, n. [Proto- + oxide: cf. F. protoxide.] (Chem.) That one of a series of oxides having the lowest proportion of oxygen. See Proto-, 2 (b) . [1913 Webster]
- protoxide of nitrogen, laughing gas, now called hyponitrous oxide. See under Laughing. [1913 Webster]