( informal ) to go beyond the limits of what is allowed or thought to be possible :
He is a performer who consistently pushes the envelope of TV comedy.
( informal ) to go beyond the limits of what is allowed or thought to be possible :
He is a performer who consistently pushes the envelope of TV comedy.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005