Lunula (anatomy)

The lunula, or lunulae (pl.) (little moon in Latin), is the crescent-shaped whitish area of the bed of a fingernail or toenail. The lunula is the visible part of the root of the nail.
In humans, it appears by week 14 of gestation, and has a primary structural role in defining the free edge of the distal nail plate (the part of the nail that grows outward).