onychorrhexis

noun
on·​y·​chor·​rhex·​is | \ ˌän-i-kə-ˈrek-səs How to pronounce onychorrhexis (audio) \
plural onychorrhexes\ -​ˌsēz How to pronounce onychorrhexes (audio) \

Medical Definition of onychorrhexis

: longitudinal ridging and splitting of the nails