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loose cannon

loose cannon

19 7.4
A person who acts unpredictably and can cause problems
  • noun
  • /luːs ˈkænən/
  • Informal
translation icon : bomba de relojería
  • After his unpredictable behavior upset several team members, everyone agreed that he was a loose cannon in the office.
  • a loose cannon
  • a dangerous loose cannon
  • a guy who is a loose cannon

This man is a loose cannon behind a driver's seat.

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Examples

  • He's a loose cannon with a short fuse, willing to scrap with anyone or anything.

  • Fine pilot, but a bit of a loose cannon.

  • But you know, he was a loose cannon.

  • Yeah, yeah, he can be a loose cannon.

  • This guy's a loose cannon.

  • I think this loose cannon needs to be locked down... before innocent people start getting hurt.

  • There is a loose cannon out there and I want him dealt with immediately.

  • We have too much time and too many people invested to have a loose cannon walking around.

    Fiction book (2002)
  • You know, I've been considered a loose cannon for a long because I say what I think.

  • But let's face it, Ryan McKnight is a loose cannon.

    Fiction book (2001)

Synonyms

lunatic
vsloose cannon
  • Offensive
51 6.2

A person who acts in a wild or reckless way

is less about deliberate recklessness and more about accidental harm
knuckleballer
vsloose cannon
  • Informal
9.3

A person who often does things that surprise other people

causes accidental trouble or damage through uncontrolled behaviour
total crazymaker
vsloose cannon
  • Informal
9.5

A person who often causes trouble and drama for others

is unpredictable and may cause unintended harm rather than social trouble

Antonyms

189 2.5

Easy to guess what will happen

Kept within limits by careful management

How Unpredictable

black swan
1 8.6
loose cannon
  • Informal
19 7.4
wildcard
2 5.1

Surface Forms

loose cannon singular
loose cannons plural

Morphology

loose + cannon

The phrase maps metaphorically from a literal 'cannon' (a dangerous, potentially damaging object) that is 'loose' (unrestrained), so a learner who knows both words can plausibly infer a person who is uncontrolled and may cause damage. However, the idiomatic nuance (unpredictability and potential collateral harm without intent) is metaphorical rather than strictly compositional, so the exact sense may not be fully predictable without prior exposure.

Etymology

The phrase loose cannon comes from a clear image on old ships: a heavy cannon that came loose in a storm would roll across the deck and smash into things. That's why the phrase now means 'a person who is unpredictable and may cause trouble'.