saltpetre

/ˈsɔːltpiːtə(ɹ)/

saltpetre

English Noun

Definition

Potassium nitrate.

Etymology

From Middle English saltpetre, alteration of Old French salpetre, from Medieval Latin sāl petrae (“salt of the rock”), named so being found as an incrustation. Alteration of the first element is from folk-etymological association with salt (which is, nevertheless, cognate to Latin sāl).