nitre vs saltpeter

nitre and saltpeter both are nouns.

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

As nouns, nitre and saltpeter are synonyms defined as:

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

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

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