spanner

from The American Heritage® Dictionary of the English Language, 5th Edition.

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

from The Century Dictionary.

• noun One who or that which spans.
• noun 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.
• noun A cross-brace.
• noun In the parallel motion of a marine steam-engine, a rod which connects the jointed rods with the radius-bar; also, in some of the earlier engines, the hand-bar or lever by which the valves were moved for the admission and shutting off of the steam.
• noun A span-worm or looper.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who, or that which, spans.
• noun obsolete The lock of a fusee or carbine; also, the fusee or carbine itself.
• noun Chiefly British usage An iron instrument having a jaw to fit a nut or the head of a bolt, and used as a lever to turn it with; a wrench; specifically, a wrench for unscrewing or tightening the couplings of hose.
• noun A contrivance in some of the earlier steam engines for moving the valves for the alternate admission and shutting off of the steam.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Australia, New Zealand, UK A hand tool for adjusting nuts and bolts.
• noun rare One who, or that which, spans.
• noun weaponry A hand tool shaped like a small crank handle, for winding the spring of a wheel lock on a musket.
• noun obsolete A device in early steam engines for moving the valves for the alternate admission and shutting off of the steam.
• noun UK A problem, dilemma or obstacle; something unexpected or troublesome (in the phrase spanner in the works)
• noun UK, mildly derogatory A stupid or unintelligent person; one prone to making mistakes, especially in language.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a hand tool that is used to hold or twist a nut or bolt