- the fine, soft, curly hair that forms the fleece of sheep and certain other animals, characterized by minute, overlapping surface scales that give it its felting property.
- fabrics and garments of such wool.
- yarn made of such wool.
- any of various substances used commercially as substitutes for the wool of sheep or other animals.
- any of certain vegetable fibers, as cotton or flax, used as wool, especially after preparation by special process (vegetable wool).
- any finely fibrous or filamentous matter suggestive of the wool of sheep: glass wool; steel wool.
- any coating of short, fine hairs or hairlike processes, as on a caterpillar or a plant; pubescence.
- Informal. the human hair, especially when short, thick, and crisp.