Trenail is a term used in carpentry to describe a wooden peg or dowel that is used to secure timber joints and prevent them from moving. However, there are several other synonyms for trenails that are used in different regions across the world. These include pegs, pins, dowels, trunnels, treenails, and tree nails. While all of these terms are used to describe the same thing, they have different origins and are used in specific contexts. For instance, treenails and tree nails refer to wooden dowels that are traditionally made by hand using a greenwood tree. On the other hand, pegs and pins are commonly used in construction and engineering to hold materials together.