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By surface analysis, fraction + -ation, or, by surface analysis, fractionate + -ion.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A separation process in which a certain quantity of a mixture is divided up into smaller quantities (fractions) in which the composition changes according to a gradient; an instance of this process. Full definition →
By surface analysis, fraction + -ation, or, by surface analysis, fractionate + -ion.
Etymology from Wiktionary, CC BY-SA 4.0.