'categorizer' originates from English, specifically formed from the verb 'categorize' plus the agentive suffix '-er' (meaning 'one who does').

'categorize' entered modern English in the 19th century via French 'catégoriser' and Modern Latin forms based on Greek; ultimately it traces back to the Greek noun 'katēgoria'.

Originally the Greek 'katēgoria' meant 'accusation' or 'a making of a statement/predicate', but over time the sense shifted to 'a class or division (category)', and 'categorizer' now means 'one who assigns items to such classes'.