1.NounThe chemical element (symbol N) with an atomic number of 7 and atomic weight of 14.0067. It is a colorless and odorless gas.
"By molar fraction, nitric oxide contains equal parts nitrogen and oxygen."
2.NounMolecular nitrogen (diatomic nitrogen), N2, a colorless, odorless gas at room temperature, which constitutes most of air (78% of it).
"The air you breathe is mostly nitrogen.; The truck was carrying tanks of nitrogen, so there was no fire risk. Police stated that if the truck had been carrying tanks of oxygen, as it often does, there might have been an explosion."
3.NounA specific nitrogen atom within a chemical formula, or a specific isotope of nitrogen.
"The two nitrogens are located next to one another on the ring."