What is the term for skin that grows up the nail and separates the free edge?

The term for skin that grows up the nail and separates the free edge is known as pterygium. This occurs when there is an abnormal growth of skin at the nail bed that can extend onto the nail plate itself, causing a visible separation. Pterygium can affect both the appearance and health of the nail, often resulting in discomfort or cosmetic concerns for the individual.

Understanding this term is important in the context of nail health and aesthetics since it can indicate underlying conditions or improper nail care. It is essential for manicurists to recognize and address such conditions properly, ensuring that clients receive appropriate advice and treatment options.

The other options represent different concepts in nail terminology. Onychophagy refers to the habit of nail-biting, which affects the shape and condition of nails but does not describe skin growth. The lunula is the visible part of the matrix at the base of the nail that appears as a white crescent shape, indicating the growth site of the nail itself. While both of these terms are relevant to nail care, they do not pertain specifically to the growth of skin that separates from the free edge.