as thick as thieves

A

as thick as thieves

Meaning

• a very secretive and close relationship between people.
• people as thick as thieves usually share confidences, are great friends, and spend much time together.
• intimate
• closely allied
• familiar
• sharing confidences
• people with a close association excluding the general population.

Examples in Sentences

1. They remained as thick as thieves for several weeks. This made us curious to know what they were doing. 
2. The foal appears great, and since it is the second to be born here in the space of a week, we’re confident the two new arrivals will be as thick as thieves. 
3. Cook and James have been friends since childhood. They’re as thick as thieves. 
4. The two women became as thick as thieves, running a café together.
5. She’d worked for him since the 1960s. As a result, they became as thick as thieves. 
6. Even though we had not seen each other for several months, we were as thick as thieves. 
7. They met as doormen and were thick as thieves for 5 to 6 years.

Origin

Originally, people used the idiom “as thick as two thieves” because it typically describes a relationship between two individuals.

By 1833, people used this phrase as a proverb, intimating that it was popular in spoken English. However, it is unclear how long this idiom existed in spoken English before making it into written English.

People initially used the phrase to mean “closely allied with.” An example is Richard Twining’s memoir, written in 1791, called Selected Papers of the Twining Family. In the memoir, the author notes that Mr. Pacchicrotti and I were quite “thick.” We rode and drank tea together often.

Regarding the word thieves, people thought of thieves as being archetypically thick. The word had some competition. Earlier versions of the phrase were as thick as “three in a bed,” “peas in a shell,” and “inkle weavers.” All were illustrations of particularly intimate things.

Family, Relationship