The British spelling of exteriorization; the act of making something external, outer, or visible; bringing inner things to the outside.
From exteriorize + -tion, using British -isation ending (from French -isation). The British variant preserves the 's' spelling influenced by French and Latin -tiō.
This is the formal British spelling used in psychology and philosophy—when psychologists talk about 'exteriorisation of aggression,' they mean turning internal feelings into external behavior.
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