closed book
See also: closed-book
English
Pronunciation
Audio (AU) (file)
Noun
closed book (plural closed books)
- (idiomatic) A person or thing that cannot be easily understood; someone or something incomprehensible or puzzling.
- "Her courteous, sedate, inexorable husband, whose will she could not bend, whom she could not cajole, whose mind was a closed book to her — a book which had lain by her hand for three years, which she had never had the curiosity to open!" — Prisoners by Mary Cholmondeley