per·i·o·nych·i·um 
(pĕr′ē-ō-nĭkē-əm)
(pĕr′ē-ō-nĭkē-əm)n. pl. per·i·o·nych·i·a (-ē-ə)
The border of epidermal tissue surrounding a fingernail or toenail.
[New Latin : PERI- + Greek onux, onukh-, nail; see nogh- in the Appendix of Indo-European roots.]