internecivity
definition
the mutual destructive relationship or conflict between parties or groups
example
The internecivity between the rival factions has led to significant losses on both sides, making any chance for reconciliation nearly impossible.
synonyms
mutual destructionconflictstrife
word origin — From Latin 'internecivus', meaning 'destructive to both sides', from 'inter' (between) and 'necare' (to kill).