( informal ) ( of a group of people ) to be very angry about sth and ready to protest strongly about it
(BE) UP IN ARMS (ABOUT / OVER STH)
Meaning of (BE) UP IN ARMS (ABOUT / OVER STH) in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005