noun
lunula; nail moon
Anatomical term for the whitish, crescent-shaped area at the base of a fingernail or toenail. Used in medical and everyday contexts.
健康な爪には、根元に白い爪半月が見える。
On healthy nails, a white lunula is visible at the base.
爪半月の大きさには個人差がある。
The size of the lunula varies from person to person.
半月 means 'half-moon' or 'crescent' in a general sense, whereas 爪半月 is the anatomical term for the nail's lunula.
Compound of 爪 (つめ, 'nail') and 半月 (はんげつ, 'half-moon'), describing the crescent-shaped area at the nail base.