Thick as thieves
Meaning
Refers to two or more people who are very close friends, share secrets, and often conspire together.
Origin
In the shadowy underworld of 19th-century London, survival for a band of thieves depended on absolute trust and unwavering loyalty. Every member had to be "thick" with the others, a term at the time signifying extreme intimacy and close connection, because a single betrayal could lead to capture or worse. Their operations, from planning heists to dividing spoils, demanded an unbreakable, conspiratorial bond. This vivid image of criminals bound by shared secrets and dangerous endeavors gave rise to the phrase, capturing the essence of two or more people so incredibly close and complicit that they might as well be partners in crime.
Examples
- After spending years as roommates, John and Mark became as thick as thieves, always knowing what the other was thinking.
- The two sisters, though different in personality, were thick as thieves when it came to planning their parents' surprise anniversary party.