Venting one's anger or frustration on someone or something that is not the real cause; taking out one's anger on others.
上司に注意されて腹が立ち、家族に八つ当たりしてしまった。
I got scolded by my boss, got angry, and ended up taking it out on my family.
人に八つ当たりするのはよくないと子供に教えた。
I taught my child that it's not good to take one's anger out on others.
彼女は失敗の責任を同僚に八つ当たりした。
She vented her frustration about the failure on a coworker.