A closed book

Definition

The expression ‘a closed book’ is used to describe something that is completely unknown or mysterious. It is often used to refer to a person that is difficult to get to know.

Examples

He was a closed book – I never could get to know him.

The candidate’s background is a closed book to us.

She was a closed book – nobody knew what she was thinking.

The new project was a closed book to us until yesterday.

His personal life is a closed book.

Origin

This phrase has been in use since the 1800s, and is thought to be derived from the idea that the contents of a book cannot be known until the cover is opened.

FAQs

What does ‘a closed book’ mean?

Answer: The expression ‘a closed book’ is used to describe something that is completely unknown or mysterious. It is often used to refer to a person that is difficult to get to know.

Where does ‘a closed book’ come from?

Answer: This phrase has been in use since the 1800s, and is thought to be derived from the idea that the contents of a book cannot be known until the cover is opened.