Noun

1. A hand tool for adjusting nuts and bolts.

   Pass me that spanner, Jake; there's just one more nut to screw in.

2. (Weapon) A hand tool shaped like a small crank handle, for winding the spring of a wheel lock on a musket.

   • 1786, Fig. 10. The spanner for spanning or winding up the spring of the wheel lock. — Francis Grose, A Treatise on Ancient Armour and Weapons, page xvi.

3. (UK) A problem, dilemma or obstacle; something unexpected or troublesome

   Half way through the production of Macbeth, the director found that the stage was smaller than he expected. This really threw a spanner in the works.

4. A stupid or unintelligent person; one prone to making mistakes, especially in language.

   You spanner, Rodney! I wanted a Chinese, not an Indian!