noun
mutual hatred; hating each other
Describes a state or act of two or more parties hating one another. Often used in contexts of interpersonal conflict or rivalry.
二人の間には深い憎み合いがある。
There is deep mutual hatred between the two.
憎み合いを続けても何も生まれない。
Continuing to hate each other won't lead to anything.
Compound of 憎み (nikumi, the continuative form of 憎む 'to hate') + 合い (ai, the continuative form of 合う 'to do mutually'). The combination yields the meaning 'mutual hatred'.