名詞 bad blood:

1. a feeling of ill will arousing active hostility
   同義詞：animosity, animus

1. There's a lot of bad blood between those two families.
   這兩家人積怨很深。
2. The two brothers fell in love with the same girl, which caused bad blood between them.
   兄弟倆都愛上了同一位姑娘，這使得兩人互相仇恨。
3. All the bad blood between the groups was forgotten when they had to unite against their common enemy.
   當要團結起來反抗共同的敵人的時候，兩派忘掉了相互間的一切仇恨。