lunula
noun
lu·nu·la
| \ ˈlü-nyə-lə
\
\
plural lunulae\ -(ˌ)lē also -ˌlī \
Medical Definition of lunula
: a crescent-shaped body part: as
a
: the whitish mark at the base of a fingernail
— called also half-moon
b
: the crescentic unattached border of a semilunar valve