rationalisation vs British spelling

rationalisation and British spelling both are nouns.

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

rationalisation (noun)	British spelling (noun)
systematic organization; the act of organizing something according to a system or a rationale	English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')
(mathematics) the simplification of an expression or equation by eliminating radicals without changing the value of the expression or the roots of the equation
the organization of a business according to scientific principles of management in order to increase efficiency
the cognitive process of making something seem consistent with or based on reason
(psychiatry) a defense mechanism by which your true motivation is concealed by explaining your actions and feelings in a way that is not threatening