In whaling, describing a whale that is striking with its tail flukes or thrashing about.
From 'a-' (in the state of) + 'fluking,' present participle of 'fluke,' where 'fluke' refers to the tail fin of a whale or a chance occurrence, possibly from Norwegian or Old Norse origins.
This nautical term perfectly shows how specific industries develop their own vocabulary—only whalers would need a single word for 'in the state of tail-striking,' but it made their work faster to communicate.
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