Fit rod

from The Collaborative International Dictionary of English v.0.48

Fit \Fit\, n.
   1. The quality of being fit; adjustment; adaptedness; as of
      dress to the person of the wearer.
      [1913 Webster]

   2. (Mach.)
      (a) The coincidence of parts that come in contact.
      (b) The part of an object upon which anything fits
          tightly.
          [1913 Webster]

   {Fit rod} (Shipbuilding), a gauge rod used to try the depth
      of a bolt hole in order to determine the length of the
      bolt required. --Knight.
      [1913 Webster]