From 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.