saltpetre vs potassium nitrate

saltpetre and potassium nitrate both are nouns.

Word	Noun	Adjective	Verb	Adverb
saltpetre	Yes	No	No	No
potassium nitrate	Yes	No	No	No

As nouns, saltpetre and potassium nitrate are synonyms defined as:

saltpetre and potassium nitrate: (KNO3) used especially as a fertilizer and explosive

Other synonyms of saltpetre include niter, nitre, saltpeter.

saltpetre (noun)	potassium nitrate (noun)
(KNO3) used especially as a fertilizer and explosive	(KNO3) used especially as a fertilizer and explosive