British spelling vs diagonalisation

British spelling and diagonalisation both are nouns.

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

British spelling (noun)	diagonalisation (noun)
English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')	changing a square matrix to diagonal form (with all non-zero elements on the principal diagonal)