potassium nitrate vs nitre

potassium nitrate and nitre both are nouns.

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

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

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

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

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