n.1. a. The dense, soft, often curly hair forming the coat of sheep and certain other mammals, such as the goat and alpaca, consisting of cylindrical strands of keratin covered by minute overlapping scales and much valued as a textile fiber.
b. Fabric or yarn made of this hair.
2. Hairy or downy material on a plant or animal, as on certain caterpillars.
3. Filamentous or fibrous material similar to the wool of a sheep or other mammal.