fight, war cry
鬨 centers on the noise and clash of combat: a fight or a war cry raised in battle.
鬨 combines 鬥 (fighting, conflict) with 共 (together, shared), suggesting the clash of opposing sides or a collective battle cry. The exact historical development is uncertain.
Inside the fighting enclosure 鬥, the component 共 (together) suggests two sides coming together in a clash. Picture warriors locked in combat, their war cries echoing as they fight.
For コウ, imagine the loud war cry echoing through a canyon: the sound 'koh!' reverberates, cueing コウ as the fighters clash inside 鬨.