[ sɔ:lt'pi:tə , sɒ- ]
( US saltpeter )
■ noun potassium nitrate or ( Chile ~ ) sodium nitrate.
Origin
ME: from OFr. salpetre , from med. L. salpetra , prob. representing sal petrae 'salt of rock' (i.e. found as an encrustation); the change in the first element was due to assoc. with salt .