ˈnitrionChem. [f. nitre n. + -ion1.] The supposed radical of nitric acid. 1868Miller Elem.Chem., Inorg. (ed. 4) 95 The chlorine displaces the nitrion..from the argentic nitrate.Ibid. 96 Each atom of nitrion..requires one atom of a monad metal like potassium to neutralize it.