spanner /(spăn"nẽr)/

span·ner

spanner

n.
  1. One who, or that which, spans.
  2. The lock of a fusee or carbine; also, the fusee or carbine itself. [Obs.]
  3. 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. [Chiefly British usage]
  4. A contrivance in some of the earlier steam engines for moving the valves for the alternate admission and shutting off of the steam.