used to say that sb should try to do sth, as a way of emphasizing that you think it is impossible to do it :
I defy anyone not to cry at the end of the film.
used to say that sb should try to do sth, as a way of emphasizing that you think it is impossible to do it :
I defy anyone not to cry at the end of the film.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005