To make or become barbarous or uncivilized; to render crude or primitive (British spelling of 'barbarize').
From 'barbarus' (Latin for barbarous) plus '-ise' (the British spelling of the verb suffix '-ize'). Both British and American forms arrived through similar paths but diverged in spelling conventions.
British English kept the '-ise' ending (like 'organise' and 'televise') while American English prefers '-ize'—this is one of the big spelling differences between the two versions of English!
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