loose cannon
noun, verb
Forms loose cannons loose cannoning loose cannoned
- noun (nautical) A cannon that breaks loose from its moorings on a ship during battle or storm, with the potential to cause serious damage to the ship and her crew.
- noun (idiomatic, by extension) An uncontrolled or unpredictable person, especially considered liable to cause unintentional or indiscriminate damage. “Jack is considered a loose cannon due to his volatile personality and his track record of being unable to maintain his composure.”
- verb (idiomatic, intransitive) To behave in a way such as to cause unintentional or indiscriminate damage.
Sources: Wiktionary — from the Wiktionary entry “loose cannon”, CC BY-SA 4.0. Details