wood: cut timber, and by extension almost anything made of wood, from a living tree to the cross
At its core this word means "wood": timber that has been cut for use, as opposed to a living, growing plant. From there it stretches to almost anything made of wood. In the New Testament it names building material set beside gold and silver, the clubs an arresting mob carries, and the wooden stocks that pin a prisoner's feet.
It also reaches back to the living plant. Revelation calls the source of endless life the "tree of life," using this same word for "wood" rather than the ordinary word for a growing tree (δένδρον). The one word can mean both cut timber and a fruit-bearing tree.
Its weightiest use is for the cross. When Peter and Paul say Jesus was hung "on a tree," they reach for this word for "wood" instead of the plain term for the cross (σταυρός). The choice is deliberate: the Old Testament declared anyone hanged on wood to be under God's curse, and calling the cross a "tree" presses that scandal onto the reader. The Hebrew word behind that image, עֵץ, covers the same broad range of wood, tree, and gallows.