A splinter (also known as a sliver) is a fragment of a larger object, or a foreign body that penetrates or is purposely injected into a body. The foreign body must be lodged inside tissue to be considered a splinter. Splinters may cause initial pain through ripping of flesh and muscle, or infection through bacteria on the foreign object. Splinters are primarily made of wood, but there are many other types, for example, other common types of splinters are, hair, glass, plastic, metal, and spines of animals.
https://en.wikipedia.org/wiki/Splinter