The Collaborative International Dictionary of English v.0.48:

spanner \span"ner\ (sp[a^]n"n[~e]r), n.
   1. One who, or that which, spans.
      [1913 Webster]

   2. The lock of a fusee or carbine; also, the fusee or carbine
      itself. [Obs.]
      [1913 Webster]

   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]
      [1913 Webster]

   4. pl. A contrivance in some of the earlier steam engines for
      moving the valves for the alternate admission and shutting
      off of the steam.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Inchworm \Inch"worm`\, n. (Zool.)
   The larva of any geometrid moth. It progresses forward by
   first bringing the rear end of the body forward, forming a
   loop, then moving the front part of the body; called also
   measuring worm, measuringworm, spanner, and looper.
   See Geometrid.
   [1913 Webster]

WordNet (r) 3.0 (2006):

spanner
    n 1: a hand tool that is used to hold or twist a nut or bolt
         [syn: wrench, spanner]