Meaning of the word lunacy in English

What does lunacy mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

lunacy

US /ˈluː.nə.sɪ/
UK /ˈluː.nə.sɪ/

Noun

the state of being mad; insanity

Example:
His behavior bordered on sheer lunacy.
It would be lunacy to invest all your savings in such a risky venture.