keep under one's hat

Preserve the secrecy of something, as in I'll tell you about it if you promise to keep it under your hat. This usage alludes to hiding a secret in one's head, covered by a hat. [Late 1800s]


Nearby words

  1. keep time,
  2. keep to,
  3. keep to oneself,
  4. keep track,
  5. keep under,
  6. keep under wraps,
  7. keep up,
  8. keep watch,
  9. keep your . . .,
  10. keeper

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