The present participle or gerund of 'concertise'; the act of arranging, organizing, or performing in concerts (British spelling).
From 'concertise' plus the present participle suffix '-ing.' This is the British English form of 'concertizing.'
The act of 'concertising' became hugely important in the 19th century when musicians started touring and performing concert series—it transformed music from an aristocratic privilege into public entertainment.
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