Fid /(?)/

Fid

n.
  1. A square bar of wood or iron, used to support the topmast, being passed through a hole or mortise at its heel, and resting on the trestle trees. (Naut.)
  2. A wooden or metal bar or pin, used to support or steady anything.
  3. A pin of hard wood, tapering to a point, used to open the strands of a rope in splicing.
  4. A block of wood used in mounting and dismounting heavy guns. (Mil.)