lunatic
word
Definition
A lunatic is a person who behaves in a very crazy, wild, or unreasonable way. It is also an old-fashioned and often offensive word for someone with a serious mental illness.
Usage & Nuances
Common in informal speech to insult or exaggerate: 'That driver is a lunatic.' Strongly negative. Avoid using it for real mental health conditions. Related adjective use exists too: 'a lunatic idea' is possible, but the noun is more common.
Example Sentences
That lunatic shouted at everyone on the bus.
basic
Only a lunatic would jump into that cold lake.
basic
The police arrested a lunatic with a knife.
basic
Who drives that fast in the rain? What a lunatic.
natural
My brother wants to sell everything and move to an island — the man's a lunatic.
natural
The crowd went lunatic after the last-minute goal.
natural