to give sb information that is supposed to be secret :
I happened to let it slip that he had given me £1 000 for the car.
She tried not to let slip what she knew.
to give sb information that is supposed to be secret :
I happened to let it slip that he had given me £1 000 for the car.
She tried not to let slip what she knew.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005