What is "fit rod"

Fit \Fit\, n.

1. The quality of being fit; adjustment; adaptedness; as of dress to the person of the wearer.

2. (Mach.)

   1. The coincidence of parts that come in contact.

   2. The part of an object upon which anything fits tightly.

      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.

n. (context shipbuilding English) A gauge rod used to try the depth of a bolt hole in order to determine the length of bolt required.