Meaning

noun a soft light woolen fabric; used for clothing

noun bath linen consisting of a piece of cloth used to wash the face and body

noun (usually in the plural) trousers made of flannel or gabardine or tweed or white cloth

originFrom Middle English flaunneol, from Anglo-Norman flanelle (compare Norman flianné), diminutive of Old French flaine, floene (“coarse wool”), from Gaulish, from Proto-Celtic *wlānos, *wlanā (“wool”) (compare Welsh gwlân, Breton gloan), from Proto-Indo-European *h₂wĺ̥h₁neh₂. More at wool.

Etymology from Wiktionary, CC BY-SA 3.0