The clear, dome-shaped front parts of the eyes that help focus light onto the retina.
From Late Latin 'cornea' (horny), from Latin 'cornus' (horn), because the tissue resembles horn in its clarity and hardness.
It's fascinating that we call the eye's lens 'cornea' after horn—medieval people couldn't see the cellular structure, so they named it for what it resembled optically, showing how observation precedes microscopic understanding.
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