n.

1. 【口】疯子；怪人；狂想家
   That crackpot thinks his neighbors are aliens.

   那位疯子认为他的邻居是外星人。

a.

1. 想入非非的，莫名其妙的，古怪的
   Yesterday Mr. Zhang received a crackpot letter, and to be worse, he did not know who was the sender.

   昨天张先生收到了一封莫名其妙的信，而且更糟糕的是，他不知道是谁寄来的。

n.

adj.