perionychium
noun
peri·onych·i·um ˌper-ē-ō-ˈni-kē-əm 
plural perionychia ˌper-ē-ō-ˈni-kē-ə
: the tissue bordering the root and sides of a fingernail or toenail
Word History
Etymology
New Latin, from peri- + Greek onych-, onyx nail — more at nail
First Known Use
circa 1879, in the meaning defined above
Medical Definition
perionychium
noun
peri·onych·i·um ˌper-ē-ō-ˈnik-ē-əm
plural perionychia -ē-ə
: the tissue bordering the sides of a fingernail or toenail