Synonyms for Classification (same or very similar meaning)
WordNet sense 1 (a group of people or things arranged by class or category):
categorization, categorisation
WordNet sense 2 (the basic cognitive process of arranging into classes or categories):
sorting
WordNet sense 3 (the act of distributing things into classes or categories of the same type):
assortment, compartmentalization, compartmentalisation
From the ODE community, based on WordNet
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