closed book, a

A secret, mystery, or puzzle, as in I can't figure her out; she's a closed book to me. This term alludes to information one can't obtain or comprehend (because the book is closed). [Early 1900s]


Nearby words

  1. close-up,
  2. closeable,
  3. closed,
  4. closed anesthesia,
  5. closed book,
  6. closed chain,
  7. closed chain compound,
  8. closed chest massage,
  9. closed circuit,
  10. closed circuit method

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