from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Slang One that is uncontrolled and therefore poses danger: "[His] bloopers in the White House seem to make him . . . a political loose cannon” ( Tom Morgenthau).
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. a cannon that breaks loose during battle or a storm and causes serious damage to the ship and its crew
- n. an uncontrolled or unpredictable person who causes damage to their own faction, political party etc.
- v. To behave in a way such as to cause damage to ones own faction, political party etc.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a person who is expected to perform a particular task but who is out of control and dangerous
From the threat posed by loose cannon rolling about a warship under sail.(American Heritage® Dictionary of the English Language, Fourth Edition)