5 definitions
Definition.com
Nitrogen oxides (n.) is smog before it has turned brown.
Definition.com
Nitrogen oxides (n.) is measured by the ton and breathed by the lungful.
Definition.com
Nitrogen oxides (n.) is what the air becomes once a flame has used it.
Definition.com
Nitrogen oxides (n.) is a fire's bill, mailed to everyone downwind.
Definition.com
Nitrogen oxides (n.) is the exhaust an engine does not need to make and makes anyway.