The word "trunnel" is a nautical term that refers to a wooden or metal pin used to secure planks or other pieces of timber to a ship's frame. Synonyms for "trunnel" include treenail, trenail, and trunnion. Treenails are wooden dowels used in shipbuilding, while trenails are metal bolts used to secure wooden parts of a ship. Trunnions, on the other hand, are pivots used in machinery and guns. These synonyms are important to know for those interested in shipbuilding, historical research, or anyone who wants to expand their vocabulary with nautical terms.