Wood (Also Lumber or timber) was a hardened fibrous; natural material found on several plants, namely trees. In the form of planks, it was among the early materials used to make sailing ships (TOS: "Balance of Terror"). As well as Houses, buildings and furniture.
In 2151, the Novan Akary was trapped under a large wooden trunk on the ground of an underground well. He was rescued by Captain Jonathan Archer and Jamin when Archer cut the trunk into two pieces by using his phase-pistol. (ENT: "Terra Nova")
Captain Jean-Luc Picard used a wooden limb, broken into two pieces, to stabilize Beverly Crusher's broken leg while trapped in an underground room on the planet Minos in 2364. (TNG: "The Arsenal of Freedom")
In a school lesson taught by the Barkonian, Talur, where she explained her understanding of basic elements by using wood as an example. She explained that "the rock in this wood can be felt by its weight and by its hardness. If we expose the wood to flame, we can encourage the fire within the wood to show itself. We can also see smoke, which is a part of the sky. The water in wood is difficult to see. Sometimes the elements are buried deep within the objects, but the four elements are always there."
Jayden, who was in reality the amnesiatic Soong-type android named Data, upon hearing Talur's explanation, told her that he did not believe her reasoning to be correct. He explained that, "I believe you are reasoning by analogy, classifying objects and phenomena according to superficial observation rather than empirical evidence." He further elaborated that "Wood, for example, does not contain fire simply because it is combustible, nor does it contain rock simply because it is heavy. Wood, like any complex organic form, is composed of thousands of different chemical compounds, none of which is fire." (TNG: "Thine Own Self")