- Describes a very close friendship or alliance.
- Often implies shared secrets or a tendency towards harmless mischief together.
Explanation
Origin
- Likely dates back to the 18th or 19th century.
- Thieves, in order to be successful and avoid capture, needed to work in close cooperation, trust each other implicitly, and share secrets.
- The idiom draws a parallel between this necessary closeness among criminals and a very strong bond between friends.
Synonyms & Related Expressions
Alternatives
Slang/Informal:
- Tight (very close)
- Ride or die (implies deep loyalty and support through anything)
- Besties / BFFs (Best Friends Forever)
- Joined at the hip
- Homies / Crew (close group of friends, urban/slang)
Milder/Standard:
- Very close
- Inseparable
- Good friends
- Close-knit
Situational Appropriateness
- Informal.
- Best used in casual conversation among friends or acquaintances.
- Might sound unprofessional or slightly dated in formal business settings.
Misunderstanding Warnings
- The word thieves could be misinterpreted literally by learners, suggesting actual criminal behavior.
- Emphasize that it refers only to the *closeness* of the relationship, perhaps with a hint of shared secrets or playful rule-bending, not actual crime.
Examples
- Those two kids are thick as thieves; they spend every moment together.
- Ever since they survived that challenging project, Sarah and Ben have been thick as thieves.
Dialogue
Alice: Mark and Jenna seem inseparable these days.
Bob: Tell me about it. They've been thick as thieves ever since that volunteer trip.
Alice: It's nice they found such a strong connection.
Social Media Examples
- Post: My daughter and her best friend are thick as thieves. Makes my heart melt! ❤️ #besties #childhoodfriends
- Comment: You two are always together! Thick as thieves! 😂
- Bio snippet: Me and my dog: thick as thieves.
Response Patterns
- Often used as an observation about others.
- Common responses include agreement: They really are, Yeah, you never see one without the other.
- Or related comments: They make a great team, I wonder what they're plotting now? (playfully).
Common Follow-up Questions/Actions
- Someone hearing this might ask for more details about the friendship: How did they become so close? or What do they always do together?.
- It might also lead to sharing anecdotes about the pair.
Conversation Starter
- No.
- Typically used to describe an existing relationship observed by the speaker.
Intonation
- Emphasis usually falls on thick and thieves.
- They're THICK as THIEVES.
Generation Differences
- Understood by most generations.
- Perhaps slightly more common among older generations (30+) but still widely recognized and sometimes used by younger people.
Regional Variations
- Common in most major English-speaking regions (UK, US, Australia, Canada, etc.).