saltpetre
noun/ˌsɔːltˈpiːtə(r)/, /ˌsɒltˈpiːtə(r)/
/ˌsɔːltˈpiːtər/
(US English saltpeter)
[uncountable]- a white powder used for preserving food and making matches and gunpowderWord Originlate Middle English: from Old French salpetre, from medieval Latin salpetra, probably representing sal petrae ‘salt of rock’ (i.e. found as an encrustation). The change in the first element was due to association with salt.
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saltpetre