The act or process of making something external or treating it as external; the result of externalizing.
From externate + -ion (Latin suffix creating nouns from verbs). Parallel construction to 'internation,' though both are quite rare in contemporary usage.
Medical terminology sometimes uses 'externation' when describing how pathogens exit or are expelled from the body—it's the formal term for what we casually call 'coming out' or 'being expelled.'
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