Origin and history of wool

Middle English wol, from Old English wull "wool, fine soft hair which forms the coat of sheep and lambs," from Proto-Germanic *wulno (source also of Old Norse ull, Old Frisian wolle, Middle Dutch wolle, Dutch wol, Old High German wolla, German wolle, Gothic wulla), from PIE *wele- (1) "wool" (source also of Sanskrit urna; Avestan varena; Greek lenos "wool;" Latin lana "wool," vellus "fleece;" Old Church Slavonic vluna, Russian vulna, Lithuanian vilna "wool;" Middle Irish olann, Welsh gwlan "wool").

Historically the most important material for clothing in cold and temperate lands. Extended to the hair of certain other animals. In reference to short, crisp, curly or kinky hair on the heads of some persons, by 1690s.

The figurative expression pull the wool over (someone's) eyes "deceive, delude, prevent from seeing clearly," is recorded from 1838, American English.

To be literally dyed in the wool (1725, as opposed to dyed in the piece) is to be so before spinning, while the material is in its raw state, which has a more durable effect; hence the figurative meaning "from the beginning; most thoroughly," is attested from 1809, used especially in U.S. politics from 1830.