/'lu:nətɪk; `lunə,tɪk/
n
1 (dated 旧) insane person 精神失常者; 疯子.
2 wildly foolish person 极愚蠢的人
*You're driving on the wrong side of the road, you lunatic! 你现在是逆行开车, 你这个蠢材!

adj
1 (dated 旧) insane 精神失常的; 疯的.
2 wildly foolish 极愚蠢的
*a lunatic proposal 极愚蠢的建议.
3 (idm 习语) the ,lunatic `fringe (derog 贬) those members of a political or some other group whose views are regarded as wildly extreme or eccentric 极端分子
*The lunatic fringe is/are ignored by most members of the party. 绝大部分党员对极端分子不予理睬.

n[C]
[Date: 1200-1300; Language: Old French;Origin: lunatique, from Late Latin lunaticus, from Latin luna ( LUNAR); because people thought mental illness was caused by the moon]
someone who behaves in a crazy or very stupid way - often used humorously
　This hotel is run by a lunatic!
old-fashioned a very offensive word for someone who is mentally ill
　a dangerous lunatic
the lunatic fringe
BrE the small group of people in a political group or organization who have the most extreme opinions or ideas
>lunaticadj [only before noun]
　lunatic behaviour