Meaning: This idiom means that two or more people are very close friends who share secrets and trust each other deeply.
Usage in Example Sentences:
- “Those two have been thick as thieves since elementary school.”
- “My sisters are thick as thieves and always keep each other’s secrets.”
- “Ever since they started working together, they’ve become as thick as thieves.”
Origin: The idiom “thick as thieves” likely originated in the 18th century, referring to the close and secretive nature of thieves working together. “Thick” here means close-knit or strongly bonded, describing a friendship with deep loyalty and shared confidences.