lunatic

名词 lunatic:

1. an insane person
   同义词：madman, maniac
2. a reckless impetuous irresponsible person
   同义词：daredevil, madcap, hothead, swashbuckler, harum-scarum

形容词 lunatic:

1. insane and believed to be affected by the phases of the moon
   同义词：moonstruck

1. 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。
2. 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！
3. The lunatic fringe are ignored by most members of the party.
   绝大部分党员对极端分子不予理睬。

lu.na.tic

adj.（形容词）
Suffering from lunacy; insane.
精神错乱的：遭受精神错乱的痛苦的；不清醒的
Of or for the insane.
精神病人的
Wildly or giddily foolish:
极端愚蠢的：狂乱地愚蠢的或惊人地愚蠢的：
例句：
a lunatic decision.
一个极其愚蠢的错误

Characterized by lunacy or eccentricity.
精神错乱者的或为精神错乱病人而设立的

来源：
Middle English lunatik
中古英语 lunatik
from Old French lunatique
源自 古法语 lunatique
from Latin lôn3ticus
源自 拉丁语 lôn3ticus
from lôna [moon] * see leuk-
源自 lôna [月球] *参见 leuk-

【引伸】
lu.natic
n.（名词）