The process of becoming barbarous or uncivilized; the act of making something barbaric or crude (British spelling).
From 'barbarise' (British spelling of 'barbarize') plus the noun suffix '-ation,' which creates abstract nouns describing processes or results. The '-ation' ending is standard in British English.
The British spelling 'barbarisation' vs. American 'barbarization' shows how English split into variants—but both refer to the same fear of cultural decline that Europeans had during periods of major change!
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