Definition

A person who is unpredictable, reckless, or uncontrollable in their actions or speech, often causing trouble or embarrassment to others. The term originates from a cannon that breaks loose on a ship and becomes a dangerous hazard.

Example Usage

He's a loose cannon in meetings—you never know what outrageous thing he'll say next.

Origin

From 18th-century naval terminology describing an unfastened cannon that could roll dangerously across a ship's deck during battle or rough seas.

Fun Fact

The phrase entered popular culture as the title of a 1990 action comedy film starring Richard Dreyfuss and Dan Aykroyd.

Source: Definition backfill (hailey)

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