Webster’s Revised Unabridged Dictionary · 1913
Internecine
In′ter·ne′cine (·nē′sĭn or ·sīn), a. [L. internecinus deadly, murderous, fr. internecare to kill, to slaughter; inter between + necare to kill; akin to Gr. νεκρός dead. See Necromancy.] Involving, or accompanied by, mutual slaughter; mutually destructive.
Internecine quarrels, horrible tumults, stain the streets with blood. Motley.