The act of laying down or reclining; in papermaking and printing, the process of transferring material to a flat surface; also the treatment of cataracts by displacing the lens.
From couch (to lie down) + -ing (gerund suffix), with multiple meanings evolved from the core idea of 'laying down' or 'placing.'
Medieval surgeons performed couching on cataract patients—they literally pushed the cloudy lens aside into the eye's corner so light could get through again, and it actually worked, though the vision wasn't perfect—it's wild that this technique lasted for centuries.
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