Definition of spanner

• n. - One who, or that which, spans.
• n. - The lock of a fusee or carbine; also, the fusee or carbine itself.
• n. - 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.
• n. - A contrivance in some of the ealier steam engines for moving the valves for the alternate admission and shutting off of the steam.