Source : Webster's Revised Unabridged Dictionary (1913)

Trenail \Tre"nail`\, n. (Shipbuilding)
   Same as {Treenail}.

Source : WordNet®

trenail
     n : a wooden peg that is used to fasten timbers in shipbuilding;
         water causes the peg to swell and hold the timbers fast
         [syn: {treenail}, {trunnel}]