monkey wrench 
noun
An adjustable spanner with large jaws which has its adjusting screw located in the jaw that is fixed.Consider a multi-wrench for those all-purpose jobs, but also add a pipe wrench, a spud wrench, strap and chain wrench, and a monkey wrench....
- They taught me how to work the wrench, the monkey wrench, so I kind of had to do a bit of training, to be honest with you.
- Last, but not least, what tool kit is not complete without a monkey wrench.
verb
(monkey-wrench) [with object] informal Sabotage (something), especially as a form of protest: they will spike trees and monkeywrench any attempts to log in wilderness areas (as noun monkey-wrenching) the five defendants received jail sentences for monkey-wrenching...
- ‘They would have let me out after a month if I'd expressed remorse,’ he says, ‘but we couldn't let them think jailing me would stop monkey-wrenching.’
- More than a narrative of organizing, demonstrating and monkey-wrenching, it places Earth First!
- For years, they were seen as the power behind attempted monkey-wrenching to the state's environmental laws and its stiff anti-corporate farming law.
Phrases
a monkey wrench in the works
Derivatives
monkey-wrencher
- What would Abbey's principal monkey-wrencher think of a trail named after him?