Niter \Ni"ter\, Nitre \Ni"tre\, n. [F. nitre, L. nitrum native soda, natron, Gr. ?; cf. Ar. nit[=u]n, natr[=u]n natron. Cf. {Natron}.] 1. (Chem.) A white crystalline semitransparent salt; potassium nitrate; saltpeter. See {Saltpeter}. [1913 Webster] 2. (Chem.) Native sodium carbonate; natron. [Obs.] [1913 Webster] For though thou wash thee with niter, and take thee much soap, yet thine iniquity is marked before me. --Jer. ii. 22. [1913 Webster] {Cubic niter}, a deliquescent salt, sodium nitrate, found as a native incrustation, like niter, in Peru and Chile, whence it is known also as {Chile saltpeter}. {Niter bush} (Bot.), a genus ({Nitraria}) of thorny shrubs bearing edible berries, and growing in the saline plains of Asia and Northern Africa. [1913 Webster]