失去信心英语可以说成 "lose confidence"。这个短语来源于拉丁语，"con-" 意为 "with"，"fid-" 意为 "faith"，因此 "confidence" 就表示 "having faith or trust in oneself or others".

下面是一些例句：

I lost confidence in myself after I failed the exam. 我在考试失败后失去了对自己的信心。

She lost confidence in her abilities after receiving negative feedback from her boss. 她在收到老板的负面反馈后失去了对自己能力的信心。

He lost confidence in his teammates after they lost the game. 他在队友们输掉比赛后失去了对他们的信心。