thick as thieves

Intimate, closely allied, as in The sisters-in-law are thick as thieves. This term uses thick in the sense of “intimate,” a usage that is obsolete except in this simile. [Early 1800s]


Nearby words

  1. thibet,
  2. thibodaux,
  3. thick,
  4. thick and fast,
  5. thick and thin,
  6. thick client,
  7. thick milk,
  8. thick register,
  9. thick skin,
  10. thick-knee

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