Meaning
Disrupt a plan, process, or system, often suddenly. Current North American idiom Regional use: Metaphor developed in the United States; spanner form is British.
Origin
The tool name monkey wrench is British and documented by 1826, but the disruptive metaphor is an Americanism from the late 19th century. An 1889 example may be literal or figurative; a clearly metaphorical 1892 report imagines a wrench thrown into a threshing machine. The wrench was not invented by a man named Moncky or by boxer Jack Johnson, and those popular name stories postdate the tool.
Research Sources
References used to check this entry’s meaning, history, or documented forms.
Variants
- put a monkey wrench in the works
- throw a monkey wrench into the machinery
- throw a spanner in the works
Usage Examples
- A week of rail closures threw a monkey wrench into the festival plans.
- The missing permit put a monkey wrench in the works just before opening day.