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Phrase(s): 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., Phrase(s): 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., Phrase(s): let on (to someone) (about someone or something)
to reveal knowledge about someone or something to someone. (See also let on (about someone or something).) • Please don’t let on to anyone about what happened last night. • I won’t let on to anyone.
McGrawhill's American Idioms And Phrasal Verbs
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general::
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.
American Heritage Idioms