不惑之年是指遇到事情能明辨不疑的年纪，一般作为40岁的代称。

出自《论语·为政》有“四十而不惑”的说法。

那么不惑之年用英语怎么说？

不惑之年可以用Age of No-doubt或者in one's 40s来表示，例如：

1.当我们步入婚姻的第二个十年的时候，我们俩也都告别而立，进入不惑之年了。
As we enter our second decade of marriage, we’ll both be in our 40s, instead of our 30s. 

2.“我在不惑之年再次经历了婚姻，再次当上父亲也让我感觉很艰难，”法帕兰说，他第一次婚姻的孩子已经26岁，第二次婚姻也有两个孩子。
"I started again in a marriage at a late time, and being a father again was kindof rough, " said Farparan, who has a 26-year-old from his first marriage and two children from his second. 

3.然而，就在二十年前，当查尔斯迈入不惑之年的时候，他却很不快乐：苦涩的婚姻早已名存实亡，来自母后的压力又逼迫他与卡米拉“保持距离”。
Two decades ago, as he turned 40, he was deeply unhappy, in a soulless, bitter marriage, and under pressure from the Queen to walk away from his affair with Camilla.