to not punish sb for sth they have done wrong, or to give them only a light punishment :
They let us off lightly.
She was let off with a warning.
to not punish sb for sth they have done wrong, or to give them only a light punishment :
They let us off lightly.
She was let off with a warning.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005