The thin layer of skin that extends from the nail fold and covers the base of the fingernail or toenail.
From Greek 'epi' (upon) + 'onyx' (nail). A medical/anatomical term coined in the 19th century to precisely name this overlooked but important nail structure.
The eponychium is that little bit of skin you're actually supposed to gently push back, not cut—dermatologists gave it a fancy Greek name because we needed precise vocabulary for talking about nail health and how to care for nails properly.
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