Dictionary.com
Thesaurus.com
Showing results for closed book. Search instead for closet room.
Synonyms

closed book

American  

noun

  1. something that is not known or cannot be understood; a mystery or puzzle.

    Abstract art is a closed book as far as I'm concerned.
closed book British  

noun

  1. something deemed unknown or incapable of being understood

  2. a matter that has been finally concluded and admits of no further consideration

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of closed book

First recorded in 1910–15

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Given founding members of the competition could not be 'relegated' from it, critics argued the tournament was a closed book for Europe's elite teams.

From BBC • Jun. 1, 2025

“As you know, I’m not normally a closed book on this stuff,” Sean told me.

From Washington Post • Apr. 26, 2023

The closed book history of that World Cup quarter-final, an event most people will have watched once, 34 years ago, states that the game was pretty much even.

From The Guardian • Apr. 26, 2020

In a way, it was a good ending, in the fact that it wasn’t completely definitive or a closed book.

From Los Angeles Times • Apr. 15, 2020

Dustfinger’s face was a closed book, and Meggie had the feeling that if anyone tried reading it he would rap their knuckles.

From "Inkheart" by Cornelia Funke

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.