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• monkey wrench
  monkey wrench

  noun

  a wrench having an adjustable jaw permitting it to grasp nuts or the like of different sizes.
• monkey-wrench
  monkey-wrench

  verb (used with object)

  to ruin (plans, a schedule, etc.) unavoidably or, sometimes, deliberately.

monkey wrench

¹ American  

noun

1. especially British, adjustable spanner.  a wrench having an adjustable jaw permitting it to grasp nuts or the like of different sizes.

2. something that interferes with functioning; obstacle.

   He threw a monkey wrench into our plans.

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monkey-wrench ² American  

[muhng-kee-rench] / ˈmʌŋ kiˌrɛntʃ /

verb (used with object)

1. to ruin (plans, a schedule, etc.) unavoidably or, sometimes, deliberately.

   The storm monkey-wrenched our plans for a picnic.

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verb (used without object)

1. to prevent, delay, or sabotage industrialization or development of wilderness areas, especially through vandalism.

monkey wrench British  

noun

1. a wrench with adjustable jaws

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Other Word Forms

• monkey-wrencher
  noun

Etymology

Origin of monkey wrench¹

First recorded in 1855–60

Origin of monkey-wrench²

First recorded in 1800–10

Example Sentences

See Examples For:

monkey wrench monkey-wrench

“I’ve learned a lot about what I might get,” she said, “but Mother Nature always has her monkey wrench in hand.”

From Los Angeles Times ● Nov. 20, 2025

But now two men on the federal death row in Terre Haute, Indiana have thrown a monkey wrench into Biden’s decision.

From Salon ● Jan. 11, 2025

One potential monkey wrench for the dollar, however, may be lurking in Japan.

From Reuters ● Aug. 18, 2023

“The last thing that a booming economy needs is to throw a monkey wrench into a system that we have that is working marvelously well.”

From Seattle Times ● Jul. 12, 2023

While everyone else was working to smooth the path toward integration, he could be the monkey wrench thrown into the works to slow the process down.

From "The Best of Enemies" by Osha Gray Davidson

Perhaps made in Crete, the idealized naturalism of a battle scene rendered in shallow three-dimensional space threw a stylistic monkey-wrench into our established understanding of Greek culture 3,500 years ago.

From Los Angeles Times ● Dec. 8, 2025

But the court has yet to decide other pending cases that could monkey-wrench the regulatory system.

From Slate ● May 30, 2024

They’re a frisky if harmless sort of monkey-wrench gang, taking their last rolls with life’s fuzzy dice.

From New York Times ● Sep. 6, 2021

She delivers a satisfying, dramatic climax that represents the comeuppance of 19th-century colonialism, as Naila and the half brothers monkey-wrench the tools of the oppressor.

From Washington Post ● Mar. 25, 2019

Material for mending tires is absolutely necessary—a good monkey-wrench, oil cans, a tire inflator, pincers, and a reasonably good supply of small wire and twine for making repairs where such material is necessary.

From Harper's Round Table, June 11, 1895 by Various