IPA: /ˈtrɛn.eɪl/
KK: /ˈtrɛnəl/
A type of wooden peg used to fasten or secure two pieces of wood together, often in shipbuilding or carpentry.
The carpenter used a trenail to join the two beams securely.
Trenail comes from Old French 'trenailler', meaning to fasten or secure. The word refers specifically to a wooden peg or dowel used to fasten two pieces of wood together.
Think of the Old French word for fastening, 'trenailler', to remember that a trenail is a peg used to secure wood together.