without sb's knowledge or permission :
Have you been talking about me behind my back?
They went ahead and sold it behind my back.
—compare to sb's face at face noun
without sb's knowledge or permission :
Have you been talking about me behind my back?
They went ahead and sold it behind my back.
—compare to sb's face at face noun
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005