in ‧ ter ‧ ne ‧ cine /ˌɪntəˈniːsaɪn◂ $ ˌɪntərˈniːs ə n◂, -ˈnesiːn◂/ BrE AmE adjective [only before noun] formal
[ Date: 1600-1700 ; Language: Latin ; Origin: internecinus , from internecare 'to destroy completely' , from necare 'to kill' ]
internecine fighting or struggles happen between members of the same group or nation:
internecine warfare