serious blunder

严重的失误：指一种严重的错误或疏忽
常用释义
严重的失误：指一种严重的错误或疏忽，可能会导致严重的后果或影响。

例句

Now, Lisa has made a really serious blunder, but I'm sure he'll give her a slap on the wrist.

现在，丽萨出了一个真是非常严重的错误。不过，我肯定他也只会轻描淡写地惩罚她一下。

So, it was not a serious blunder to entitle him as Duke Spirit.

所以称他灵公，也不应算是什么大错。

吃错了药可是很严重的错误。

You have been guilty of a serious blunder.

你犯了个大错误。