1. Also called, esp. Brit.,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.
Pronunciation: (mung'kē-rench"),[key] —v.t. to ruin (plans, a schedule, etc.) unavoidably or, sometimes, deliberately: The storm monkey-wrenched our plans for a picnic.
—v.i. to prevent, delay, or sabotage industrialization or development of wilderness areas, esp. through vandalism.