saltpetre vs nitre

saltpetre and nitre both are nouns.

Word	Noun	Adjective	Verb	Adverb
saltpetre	Yes	No	No	No
nitre	Yes	No	No	No

As nouns, saltpetre and nitre are synonyms defined as:

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

Other synonyms of saltpetre include niter, potassium nitrate, saltpeter.

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