a closed book(redirected from the closed book)
a closed book
Someone or something that is difficult to know or understand. She's such a private person that I don't know much about her. I guess she's a closed book. I'm a scientist, so art will always be a closed book to me.
closed book, a
A secret, mystery, or puzzle, as in I can't figure her out; she's a closed book to me. This term alludes to information one can't obtain or comprehend (because the book is closed). [Early 1900s]
See also: closed
a closed bookBRITISH
If something or someone is a closed book to you, you know or understand very little about them. Economics were a closed book to him. He is such a closed book, that guy. Compare with an open book.
a closed booka thing of which you have no knowledge or understanding.
1944 Frank Clune The Red Heart The desert is an open book to the man of the Vast Open Spaces, but to the schoolmaster it was a closed book.