nitre

from Latin nitrum borrowed from Ancient Greek νίτρον nítron see natron, nitrate, nitric and nitrogenous. The nitrum designated in antiquity a range of alkaline carbonates, nitrates or borates. Medieval alchemy evolved the meaning of the term towards alkaline nitrates, and in particular the component known of black powder or gunpowder, that is to say potassium nitrate or the nitre of French-speaking mineralogists. The English language, more adept on this last point with niter, still keeps "soda niter" to designate practically sodium nitrate, but German still designates the mineral species nitrokalit or potassium nitrate.