To reveal, disclose incidentally. Cf. betray, v. 6.

transitive. To reveal (information, a secret) by speaking indiscreetly; to blab out.

to let fall. To ‘drop’, utter (a word, a hint), esp. carelessly or inadvertently.

transitive. To disclose, reveal, or show, unintentionally or incidentally; to allow to be seen or perceived, to betray.

slang. To disclose, reveal, let out. (Cf. 13.)

Originally U.S. slang. To betray, expose (oneself, another person) to detection or ridicule; to let slip (a secret), esp. through carelessness or…