知己用英语怎么说

知己在英语中叫做 confidant。它来源于法语，意思是知心人，信任的人。例句：

I need to talk to my confidant about something personal. (我需要和我的知心人谈谈个人事情。)
She is my closest confidant. (她是我最亲密的知心人。)
I confide in my confidant about everything. (我和我的知心人交流所有事情。)