fluoridization vs fluoridisation

fluoridization and fluoridisation both are nouns.

Word	Noun	Adjective	Verb	Adverb
fluoridization	Yes	No	No	No
fluoridisation	Yes	No	No	No

As nouns, fluoridization and fluoridisation are synonyms defined as:

fluoridization and fluoridisation: the addition of a fluoride to the water supply (to prevent dental decay)

Other synonyms of fluoridization include fluoridation.

fluoridization (noun)	fluoridisation (noun)
the addition of a fluoride to the water supply (to prevent dental decay)	the addition of a fluoride to the water supply (to prevent dental decay)