Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:
In atmospheric chemistry:
- NO x (or NOx) refers to the sum of NO and NO2.
- NO y (or NOy) = the sum of all oxidized atmospheric odd-nitrogen species (e.g. NOx + HNO3 + HNO2 + etc.)
- NO z (or NOz) = NOy − NOx