noun
monkey wrench; adjustable spanner
A wrench with an adjustable jaw, used for turning nuts and bolts of various sizes. The term is a compound of 自在 (adjustable) and スパナ (spanner/wrench).
水道の修理に自在スパナを使った。
I used a monkey wrench to repair the plumbing.
この自在スパナは口の幅を簡単に
This adjustable spanner can easily change its jaw width.