Courtesy of Grandiloquent Word of the Day.

Acnestis is a rarely used English terms refers to the point of the human back that lies between the shoulders and the lower back that cannot be reached to be scratched.

When open water swimmers are swimming with a good body position – either with their head up while sighting or with their head down when swimming in a streamlined position – their acnestis is generally exposed on the surface of the water.

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