spanner

A wrench having a hook, hole, or pin at the end for meshing with a related device on another object.

A wrench.

One who or that which spans.

An instrument for clasping and turning a nut on a screw, or for any similar purpose, as turning the wheel in cocking the old wheel-lock firearms, fastening and unfastening the couplings of fire-hose, etc.; a screw-key or screw-wrench. Spanners are made either with a hole to fit the shape of the nut, as square or hexagonal, or with movable jaws that can be tightened over a nut or a coupling of any shape.

A cross-brace.