Potassium nitrate, especially as a naturally occurring mineral.Compare with saltpeter‘The German U-boats were shooting on the boats, so most of the niter they were trying to import to make nitroglycerin was at the bottom of the ocean.’
- ‘Various reflecting surfaces were used: polished metallic rocks such as obsidian, pyrite, and iron; rock crystal; and an alloy of rose copper and tin, plus an alchemical brew consisting of white arsenic, red tartar, and nitre.’
- ‘Nitre, or niter, is also used to manufacture gunpowder.’
- ‘Maybe Boone noticed crystals of potassium nitrate there, because the deep, loose floor was soon being mined for niter to make gunpowder.’
- ‘The fresh juice supplying 30 percent potassium and the mucilage a good amount of niter and sodium.’
Late Middle English from Old French, from Latin nitrum, from Greek nitron.
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