Meaning of the word "keep something under your hat" in English

What does "keep something under your hat" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

keep something under your hat

US /kiːp ˈsʌmθɪŋ ˈʌndər jʊər hæt/
UK /kiːp ˈsʌmθɪŋ ˈʌndər jʊər hæt/
"keep something under your hat" picture

Idiom

to keep something a secret

Example:
Please keep this under your hat; I don't want anyone else to know yet.
She asked him to keep the news under his hat until the official announcement.