- a crystalline compound, KNO3, produced by nitrification in soil, and used in gunpowders, fertilizers, and preservatives; saltpeter; niter.
- a colourless or white crystalline compound used in gunpowders, pyrotechnics, fertilizers, and as a preservative for foods, esp as a curing salt for ham, sausages, etc (E252). Formula: KNO 3
