let slip

present singular third person lets slip · participle present letting slip

1. idiomatictransitiveTo divulge a secret, as by accident or mistake.

   It was let slip that they were planning to take over the business.

   1 more example

   The frizzle-headed man-eaters were loath to leave their fleshpots so long as the harvest of human carcases was plentiful. Sometimes, when the harvest was too plentiful, they imposed on the missionaries by letting the word slip out that on such a day there would be a killing and a barbecue.

   1909 December 29, Jack London, “The Whale Tooth”, in South Sea Tales, New York, N.Y.: The Macmillan Company, published October 1911, →OCLC, page 61

2. UKobsoleteslangTo let fly; to attack or challenge someone.

   I would take it kind of your worship to let me be present at his examination, that if he clear himself of one murder I may let slip at him with the other.

   1862, Thomas Hood, John Clubbe, Tom Hood, Works: Comic and Serious, in Prose and Verse. Edited, with Notes, page 263