ionisation vs British spelling

ionisation and British spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
ionisation	Yes	No	No	No
British spelling	Yes	No	No	No

ionisation (noun)	British spelling (noun)
the process of ionizing; the formation of ions by separating atoms or molecules or radicals or by adding or subtracting electrons from atoms by strong electric fields in a gas	English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')
the condition of being dissociated into ions (as by heat or radiation or chemical reaction or electrical discharge)