Merriam-Webster Collegiate Dictionary - wool

 noun  Usage: often attributive  Etymology: Middle English wolle, from Old English wull; akin to Old High German wolla ~, Latin vellus fleece, lana ~  Date: before 12th century  1. the soft wavy or curly usually thick undercoat of various hairy mammals and especially the sheep made up of a matrix of keratin fibers and covered with minute scales  2. a product of ~; especially a woven fabric or garment of such fabric  3.  a. a dense felted pubescence especially on a plant ; tomentum  b. a filamentous mass — usually used in combination; compare mineral ~, steel ~