forearm

前臂、小臂

He broke his left forearm while skateboarding last summer.

他去年夏天玩滑板时弄断了左前臂。

预先武装、预作准备正式；常用被动

Forewarned is forearmed, so read the safety notice carefully.

事先有警觉就是事先有准备，所以请仔细阅读安全须知。