|intər|ne]ˌsēn, -nē], ]ˌsīn, ]s ə n, ]sə̇n; |intərnə̇|sēn; ə̇n.ˈtərnəˌsēn, -nəsə̇n, -nəˌsīn\ adjective
Etymology: Latin internecinus, from internecare to destroy, kill (from inter- + necare to kill, from nec-, nex violent death) + -inus -ine — more at noxious
1.
a. : marked by great slaughter : deadly
the alternatives only of internecine war or absolute surrender — W.E.Gladstone
b. : involving or accompanied by mutual slaughter : mutually destructive
zealots who stabbed each other in internecine massacre — F.W.Farrar
2. : of, relating to, or involving conflict within a group ; broadly : internal
absorbed in incurable, rancorous internecine feuds — Barbara Ward
a bitter internecine struggle among artists — Roger Fry