
Meaning of Idiom ‘A Closed Book’
A closed book is someone or something about which you know nothing or which you do not understand; a secret or mystery; a subject that someone does not want to talk about or be asked about. 1Ayto, John. Oxford Dictionary of English Idioms. Oxford: Oxford U, 2010.,2Kirkpatrick, Elizabeth M. The Wordsworth Dictionary of Idioms. Ware: Wordsworth, 1995.,3Ammer, Christine. American Heritage Dictionary of Idioms. Boston: Houghton Mifflin Harcourt, 2013.,4Jarvie, Gordon. Bloomsbury Dictionary of Idioms. London: Bloomsbury, 2009.
See the antonym an open book.
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Sentence Examples
“Quantum physics can be a closed book even to those who study it.”
“Nobody really knows Michelle very well. She’s a closed book.”
“For years, the mysterious past of the island was a closed book.”
“Listen, we can talk about anything but my divorce. That is a closed book.”

Origin
Used since the early 1900’s, the idiom alludes to being unable to access the information in a book because the book is closed.
More Idioms Starting with C
More Close Idioms
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- Every Name in the Book, been called
- Are You Writing a Book?
- Bookworm
- Read Someone Like a Book
- Open Book, an
