saltpetre

Etymology
From, alteration of , from , named so being found as an incrustation. Alteration of the first element is from folk-etymological association with (which is, nevertheless, cognate to ).

Noun

 * 1)  Potassium nitrate.
 * 2)  Sodium nitrate.

Synonyms

 * (potassium nitrate): Chilean saltpeter/Chilean saltpetre, nitrate of potash, niter/nitre, potassium nitrate
 * (sodium nitrate): caliche, Chile saltpeter/Chile saltpetre, soda niter/soda nitre, sodium nitrate

Verb

 * 1)  To treat with saltpetre.