1N-COUNT (旧时僧侣苦行修炼时穿的）刚毛衬衫 A hair shirt is a shirt made of rough uncomfortable cloth which some religious people used to wear to punish themselves. (旧时僧侣苦行修炼时穿的）刚毛衬衫
He was sent barefoot wearing only a hair shirt into the wilderness as a penance.
为了赎罪，他跣足褐衣，被流放到了荒野中。
2N-COUNT 自我惩罚 If you say that someone is wearing a hair shirt, you mean that they are trying to punish themselves to show they are sorry for something they have done. 自我惩罚
No one is asking you to put on a hair shirt and give up all your luxuries.