remorse

悔恨、懊悔、自责

He showed no remorse for the pain he had caused.

他对自己造成的伤害毫无悔意。

良心不安、愧疚

She was kept awake by remorse over the harsh words.

她因为那些重话而良心不安，整夜难以入睡。

毫不留情、毫无悔意

The gang robbed the elderly couple without remorse.

那帮人毫不留情地洗劫了那对老夫妇。