thick as thieves

1. Intimate, closely allied, as in The sisters-in-law are thick as thieves. This term uses thick in the sense of “intimate,” a usage that is obsolete except in this simile. [Early 1800s]

Example Sentences

The two used to be “thick as thieves,” he said.

From Los Angeles Times

"They were thick as thieves," explains Harsha Evangeli, who taught the teenager art.

From BBC

“She’s scared you’ll be like Charlotte. It’s difficult for Kat to make friends, but the two of them were thick as thieves. It really helped her come out of her shell. Then one day…Char was gone.”

From Literature

Joey King, who plays youngest daughter Halina, values having a close relationship with her grandmother and says they are “thick as thieves.”

From Seattle Times

Mr. Luttrell recalled that he and his peers were “thick as thieves” on the campaign trail.

From Washington Times

Related Words

• dear 
• devoted 
• familiar 
• related