A
treenail, also
trenail,
trennel, or
trunnel, is a wooden peg, pin, or
dowel used to fasten pieces of wood together, especially in
timber frames,
covered bridges, wooden
shipbuilding and
boat building. Many such buildings and bridges are still in use.
Locust is a favorite wood when making trunnels in shipbuilding due to its strength and rot resistance and red oak is typical in buildings.