brain-dead
adjective uk/ˈbreɪn.ded/ us/ˈbreɪn.ded/
脑死亡的
If someone is brain-dead, they have serious and permanent damage to their brain, and need machines in order to stay alive.
humorous（尤指因疲劳或烦恼而造成的）头脑不灵敏，愚钝
If someone is brain-dead, their mind is not working effectively, usually because they are very tired or very bored.
By the time I leave work I'm completely brain-dead. 到下班时，我的头脑都迟钝了。