A subject or person about which one knows nothing: accounting has always been a closed book to me
More example sentences
- The political parties are closed books as far as the majority is concerned.
- She explained: ‘I still think to this day that there is more to it than what came out but you are dealing with the army and it is a closed book.’
- I don't like it, and though I don't consider myself a public person, there is no aspect of my life that is a closed book.
Definition of closed book in:
- The US English dictionary