Sylvan or Silvan refers to an association with the woods. Specifically, that which inhabits the wood, is made of tree materials, or comprises the forest itself. The term can also refer to a person who resides in the woods or a spirit of the wood. In mythology, the term also refers to deities or spirits of the woods.
|Look up sylvan in Wiktionary, the free dictionary.|
The term in English is from the Latin silva meaning "forest, woods." This root is found in place names in Canada such as Sylvan Lake  (as in wooded lake) in Alberta, Sylvan Valley Regional Park Reserve in Saskatchewan, and in the United States like Pennsylvania (lit. "Penn's woods") and Spotsylvania. The first names Sylvester and Sylva(i)n, and the female name Sylvia/Silvia, are also from the Latin word.
Notable examples 
In the Chronicles of Narnia, silvans are tree spirits, appearing primarily in the fourth book of the series, Prince Caspian. In J. R. R. Tolkien's Middle-earth books, there is a division of Elves residing in forested realms referred to as Silvan Elves.
In the computer role-playing game "Dragon Age: Origins," the player's party battles living trees known as Sylvans in the Brecillian Forest. In the lore of the game, the trees are actually possessed by demonic spirits which have gone mad because they are trapped in the tree without being able to see or hear.
In the popular toy line called Sylvanian Families, Sylvanian refers to the toy line earlier specializing in woodland creatures. It branched out to other animals later on.
In the MMORPG Guild Wars 2, Sylvari (a different spelling of Sylvan) are a playable race of botanical humanoids that are awakened from the Pale Tree.