Source : Webster's Revised Unabridged Dictionary (1913)

Niter \Ni"ter\, Nitre \Ni"tre\, n. [F. nitre, L. nitrum native
   soda, natron, Gr. ?; cf. Ar. nit?n, natr?n natron. Cf.
   {Natron}.]
   1. (Chem.) A white crystalline semitransparent salt;
      potassium nitrate; saltpeter. See {Saltpeter}.

   2. (Chem.) Native sodium carbonate; natron. [Obs.]

            For though thou wash thee with niter, and take thee
            much soap, yet thine iniquity is marked before me.
                                                  --Jer. ii. 22.

   {Cubic niter}, a deliquescent salt, sodium nitrate, found as
      a native incrustation, like niter, in Peru and Chili,
      whence it is known also as {Chili saltpeter}.

   {Niter bush} (Bot.), a genus ({Nitraria}) of thorny shrubs
      bearing edible berries, and growing in the saline plains
      of Asia and Northern Africa.

Nitre \Ni"tre\, n. (Chem.)
   See {Niter}.

Source : WordNet®

nitre
     n : (KNO3) used especially as a fertilizer and explosive [syn: {potassium
         nitrate}, {saltpeter}, {saltpetre}, {niter}]