nitre

{ } n. [ F. nitre, L. nitrum native soda, natron, Gr. &unr_;; cf. Ar. nitūn, natrūn 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 ]