lunatic

n.疯子

adj.疯狂的；极蠢的

People in this town know him as a lunatic. 这个镇上的人们称他为疯子。

I really don't know what kind of man he really is; on one occasion, he is normal, and on another, he acts like a lunatic. 我真不了解他到底是怎样的人; 一会儿正常，一会儿又像个疯子。

The man's lunatic behavior is a menace to society. 那个人的疯狂行为构成对社会的威胁。