someone or something easily understood or interpreted; something very clear: The child's face is an open book.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use open book in a sentence
We’re kind of like an open book and the chapter hasn’t been written yet.A small town in denial comes face to face with the virus | Will Englund | February 26, 2021 | Washington Post
Couple that with the digital breadcrumbs we actively share about the diets we try, the shows we binge and the tweets we love, and our lives are an open book.Can privacy coexist with technology that reads and changes brain activity? | Laura Sanders | February 11, 2021 | Science News
John Huston recalls in his autobiography, An open book, a time when he asked Mitchum to crawl across the grass on his elbows.The Stacks: Mr. Bad Taste and Trouble Himself: Robert Mitchum | Robert Ward | July 19, 2014 | THE DAILY BEAST
It seems that open book Toronto has now included the entire entry.Why David Bowie’s Top 100 Books List Had Only 75 Books | Thomas Flynn | October 3, 2013 | THE DAILY BEAST
Good luck with that once your origins are an open book to officialdom.
Schoolchildren today take open-book tests or with a calculator.Is the Internet Making Us Forgetful? Michael S. Malone’s ‘The Guardian of All Things’ | Austen Rosenfeld | August 25, 2012 | THE DAILY BEAST
When you contemplate running for president, your life becomes an open book.
He lifted his head, looked around him, and was just going to switch off the light, when he noticed the open book on his table.Bella Donna | Robert Hichens
In the light of that astounding discovery, she now read the mysterious Dr. Weirmarsh as she would an open book.The Doctor of Pimlico | William Le Queux
Quickly I lean over; the open book in my hands entirely hides the keys.Prison Memoirs of an Anarchist | Alexander Berkman
His sad countenance, like theirs, was an open book in which the Russian could clearly read this important fact.The Life of Napoleon Bonaparte | William Milligan Sloane
Three days later, Eustace, writing alone in the library at night, saw it sitting on an open book at the other end of the room.Masterpieces of Mystery, Vol. 1 (of 4) | Various
British Dictionary definitions for open book
a person or thing without secrecy or concealment that can be easily known or interpreted
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
Other Idioms and Phrases with open book
Something or someone that can be readily examined or understood, as in His entire life is an open book. This metaphoric expression is often expanded to read someone like an open book, meaning “to discern someone's thoughts or feelings”; variations of this metaphor were used by Shakespeare: “Read o'er the volume of young Paris' face,” (Romeo and Juliet, 1:3) and “O, like a book of sport thou'lt read me o'er” (Troilus and Cressida, 4:5). [Mid-1800s] For an antonym, see closed book.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.