失传的英文：
be lost

参考例句：

Chinese kung fu is magnificent and profound but it's unfortunate that a lot of it has not been passed down.
中国的功夫博大精深，可惜有很多已经失传了。

On the other hand, people who grieve over and lament the loss of traditions would do well to do some re-thinking.
那些面对传统失传而痛心疾首的人也要好好反思。

"Ah, but madame, does mankind ever lose anything?
“哦，真的，人类有哪样东西是永远失传了的呢？

lost是什么意思：
adj. 迷路的；丢失的；丧失的；错过的
v. [lose] 的过去式和过去分词形式

I'm lost as a light is lost in light.
我如同灯盏迷失在光明里。

The lost ring was never found.
遗失的戒指再也没有找到。

The motion was lost by a majority of two.
动议以两票之差被否决了。

lost bird | miss | to miss
未中| 未中靶

You cannot be lost on a straight road
走直路,不迷途