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Thick as thieves



Very close friends who share secrets etc.

Thick as thieves

This idiom originated in the 1800s. At that time, thieves often worked together in gangs and were extremely close, telling each other everything and completely replying on each other. ‘Thick’ in this case means ‘very close’ or ‘closely packed’, for example thick hair, thick grass etc. These were put together to make the phrase ‘thick as two thieves’ which was later shortened to ‘thick as thieves’.


“Jane and Thomas are as thick as thieves – they do everything together!”
“Susan and I were thick as thieves when we were younger. We lived on the same street, went to the same school and spend most of our time together.”
Carrie: “How’s John? I haven’t seen him for a while.” Daniel: “Neither have I. We had an argument last month and we haven’t spoken since.” Carrie: “Wow, I’m shocked. You two used to be thick as thieves!”