an event or a piece of news which is sudden and unexpected; a complete surprise :
Her dismissal came as a bolt from the blue.
an event or a piece of news which is sudden and unexpected; a complete surprise :
Her dismissal came as a bolt from the blue.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005