An example of a loose cannon is your drunk uncle at your wedding who may or may not start to yell at everyone and throw a fit.
Origin of loose cannonby analogy with a cannon on an old warship that had come loose from its mounting and was rolling around dangerously
Origin of loose cannonFrom the threat posed by loose cannon rolling about a warship under sail.
(plural loose cannons)
- (nautical) A cannon that breaks loose from its moorings on a ship during battle or storm, which has the potential to cause serious damage to the ship and its crew.
- (idiomatic, by extension) An uncontrolled or unpredictable person who causes damage to their own faction, political party, etc.
- Jack is considered a loose cannon due to his volatile personality and his track record of being unable to maintain his composure.
(third-person singular simple present loose cannons, present participle loose cannoning, simple past and past participle loose cannoned)
- (idiomatic) To behave in a way such as to cause damage to one's own faction, political party etc.