unexplained

adj

1. having the reason or cause not made clear

e.g. an unexplained error

2. not explained

e.g. accomplished by some unexplained process

1. 莫名其妙的；原因不明的
If you describe something as unexplained, you mean that the reason for it or cause of it is unclear or is not known.

unexplained

e.g. The demonstrations were provoked by the unexplained death of an opposition leader...
一位反对派领袖莫名身亡，引发了示威游行。
e.g. Soon after leaving Margate, for some unexplained reason, the train was brought to a standstill...
离开马盖特不久，不知什么原因，火车突然停了下来。

1. 未解释的：unexpected fluctuation 意外波动 | unexplained 未解释的 | unexpressive 没表情的

2. 原因不明：sort 排序 | unexplained原因不明 | occur发生

3. 未说明的,未解释的：unexpected shutdown;意外的停车[关闭] | unexplained;未说明的,未解释的 | unf;统一标准细牙螺纹