open book


noun
  1. someone or something easily understood or interpreted; something very clear: The child's face is an open book.

Origin of open book

1
First recorded in 1850–55

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use open book in a sentence

  • 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.

British Dictionary definitions for open book

open book

noun
  1. 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

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.