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Related to let on: lean on
let on (to someone) (about someone or something)
to reveal knowledge about someone or something to someone. Please don't let on to anyone about what happened last night. I won't let on to anyone.
let on something
to pretend something. She let on that she was a college graduate. He looked quite tired, but that wasn't how he let on.
(about someone or something) (to someone) to confirm or reveal something about someone or something. I won't let on about Kate. You promised you wouldn't let on about Sally and her new job! He was having money troubles, but he never let on about it to us.
1. Reveal one's true feelings or a fact, allow something to be known, as in Don't let on that you met her before. This usage is probably a shortening of let it on someone. [c. 1700]
2. Pretend, as in He let on that he was very angry, but in fact he didn't care a bit. [First half of 1800s] Also see let in on.
To allow something to be known; admit or give away something: Don't let on that you know the undercover police officer.