Definitions
American Heritage® Dictionary of the English Language, Fourth 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).
Wiktionary
- n. nautical a cannon that breaks loose during battle or a storm and causes serious damage to the ship and its crew
- n. idiomatic, by extension an uncontrolled or unpredictable person who causes damage to their own faction, political party etc.
- v. idiomatic To behave in a way such as to cause damage to ones own faction, political party etc.
WordNet 3.0
- n. a person who is expected to perform a particular task but who is out of control and dangerous
Etymologies
- From the threat posed by loose cannon rolling about a warship under sail. (American Heritage® Dictionary of the English Language, Fourth Edition)
Examples
Sorry, no example sentences found.
Lists
These user-created lists contain the word ‘loose cannon’.
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POL - cool collocations (Adj+Noun)
strident criticism, devolved approach, lax control, serious misgivings, incessant negotia..., fundamental task, controversial plan, fierce criticism, lengthy consultation, public confidence, central point, final push and 183 more...
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EN - cool expressions
Trendy, funny or highly descriptive collocations
overstep the mark, open a big can of..., bad hair day, the icing on the ..., low-hanging fruit, ripple effect, big cheese, tackle an issue h..., root-and-branch r..., throw good money ..., open Pandora's box, place on the back... and 147 more...
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phraseologue ⊃ the one-two punch
short (mostly two-word) collocations, pat phrases, idioms &c. that I like
merry chase, glancing blow, beast mode, feedback loop, false flag, dear god, nothing human, deflector shield, hatchet job, not cricket, bang on, a tinker's damn and 322 more...
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Insulting nicknames for politicians
Some of these terms are old-fashioned, but they might still come in handy.
snollygoster, slang-whanger, bloviator, fence-sitter, flip-flopper, log roller, mossback, lame duck, mugwump, spinmeister, ward heeler, loose cannon
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Fireclature
Names for firecrackers, real or imagined . . .
The more martial, erotic, ferocious, or just plain ridiculous, the betterbad mutha trucka, hen laying egg, nuclear reactor, shock n awesome, lulu mccoy, the big o, festival balls, tiger fury, tazmanian devil, blondie, magic 8-ball, bad mutha and 58 more...
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Wrongheads
Insults that make me laugh. Some of these are re-contextualized because they sound like insults to me.
wretched, dasdardly, sniveling, dingbat, rankle, vapid, ninny, nincompoop, dolt, imbecile, fucktard, scoundrel and 173 more...
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The Sog Collection
My big word list.
chaos, flaccid, empirical, flotsam, cacophony, grumble, assuage, awe, romance, mortality, coalesce, fortuitous and 3282 more...
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Three Sheets to the Wind
Common words or phrases of nautical origin that have taken on different or metaphorical meanings. Chained_bear and I tossed a coin over who would make the list. I won (or lost, depending on how you...
scuttlebutt, taken aback, brass monkey, boot camp, clean bill of health, three sheets to t..., the devil to pay, between the devil..., by and large, the whole nine yards, mind your ps and qs, slush fund and 116 more...
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Historical Military Terms of Interest
Many (if not all) of these terms were selected from A pocket dictionary, for military officers, containing a definition of all the tactical terms now in use, with other matter belonging to the art ...
zig-zags, yeoman, xerxes, xeiff, xenophon, worm, watch-word, windage, wheeling, wad-hock, wadding, volley and 242 more...
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Fun phrases & Idioms2
deep-six, jump the gun, play hardball, race against time, slam dunk, blind-sided, rock the boat, cold hard cash, gravy train, monkey business, smell a rat, bang for the buck and 87 more...
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idiom magic
Idioms I like.
edgewise, old stick in the mud, druthers, just desserts, loose cannon, follow suit, goody two-shoes, one fell swoop, oyster, nothing could be ..., one of the best-k...
Tweets
Looking for tweets for loose cannon.

chained_bear See 15th secure your guns (and its list) for more info. Oct 10, 2008
chained_bear I was on land, and so was the gun, which is actually a really small one (3- or 6-pound shot vs. 18- or 24-pounders on warships or siege lines). And the trunnion itself didn't actually bust loose. Only one trunnion cap key was not fully locked in, and the force of a normal firing was enough that the barrel jumped a bit, jostling the key out and lifting the trunnion cap some. No harm done, but it's a sobering experience to realize what could've happened—and what must have happened (at least on occasion) in the past when these things were in common use. Sep 21, 2008
reesetee Zoiks! Thanks, c_b. I found out about the literal meaning behind "loose cannon" when I started my "Three Sheets to the Wind" list. Sounds terrifying, to be sure. At least you were on land when the trunnions came out of the trunnion cap (is that right)? Sep 21, 2008
chained_bear The metal plate that anchors the cannon to the gun carriage is called a trunnion cap. The big "pin"-like protuberances on either side of the barrel, which the cap is locked on top of, are the trunnions. *whew* Sep 21, 2008
chained_bear Thankfully not, reesetee--at least not a *really* loose one. One of the pins came out of the... I wish I knew the name for the metal plate that holds the cannon onto the gun carriage... Anyway those things jump like hell if they're not strapped down.
But I think "loose cannon" didn't refer to this kind of mishap, but to the kind of large cannons used on navy ships, gunships, that used ropes to keep them in place so they didn't roll all over the deck and crush people. It wasn't just the ordinary recoil or malfunction of the gun or hardware that made a loose cannon, but the failure of the ropes. I can't imagine being near one of these machines if it were *really* loose. It's truly deadly. And makes the phrase, in reference to a person who's uncontrollable to the point of being dangerous, really a powerful saying.
P.S. Asativum... HEE!! :) Sep 20, 2008
asativum Is a loose canon like a drunk monk? Sep 20, 2008
reesetee Have you been chased by a loose cannon in your day, c_b? Sep 20, 2008
chained_bear These are not really at all fun to be around... Though I like the idea of calling a person this. Sep 20, 2008
whichbe whoops! Sep 20, 2008