A person who writes columns, especially newspaper or magazine opinion pieces; an essayist or commentator.
From 'column' (a regular newspaper feature) + the suffix '-arian' meaning 'one who practices or specializes in.' A 20th-century profession-based term.
The term 'columnarian' never quite caught on compared to 'columnist,' but it shows how English constantly tries out '-arian' to create profession names—we got 'librarian' but not 'columniarian'!
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