means The soft, crimped, insulating fiber that grows as a sheep's coat, spun into yarn and woven or knitted into warm, water-resistant cloth.

from From Old English 'wull,' tracing back to the Proto-Germanic '*wullo' — which is why German has 'Wolle' and Dutch 'wol.' Push further back and it's likely a cousin of Latin 'lana' and the root behind 'lanolin,' all spun from a Proto-Indo-European source ('*hwlhna'-ish, as reconstructed) meaning the woolly stuff itself. In short, humans have been naming this fleece for as long as we've had words and sheep to share them with.