up in arms

Adjective

up in arms (not comparable)

1. (figuratively) Angry; incensed; preparing for a fight.
   • Near-synonym: in the streets
   • The union members are up in arms over threats of pay cuts.

   Synonyms:

   in the streets

2. (figuratively) Vigourously protesting against something.
   • Is file-sharing, which has the recording industry so up in arms, the “dark side” of open-source attitudes?2003 September 28, David Diamond, “The Way We Live Now: 9-28-03: Questions for Linus Torvalds; The Sharer”, in The New York Times Magazine
   • Many artists are up in arms about the new AI programs — and with good reason. Some are furious that their works have been used as training data without their permission.2023 March 24, Nathan J. Robinson, “The Problem With AI Is the Problem With Capitalism”, in Jacobin
3. (uncommon, literal) Armed for battle; prepared for or engaged in warfare.
   • March on, march on, ſince we are vp in Armes,
     If not to fight with forraine Enemies,
     Yet to beat downe theſe Rebels here at home.c. 1593 (date written), William Shakespeare, “The Tragedy of Richard the Third: […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and...
   • News was brought him, that the Scythians, and barbarous nations of the North, were again up in arms, and invading the empire with furious impetuosity.1769, [Oliver] Goldsmith, chapter 18, in The Roman History, from the Foundation of the City of Rome, to the Destruction of the Western Empire. […], volume II, London: […] S. Baker and G. Leigh, […]...