[vane] n [ME (southern dial.), fr. OE fana banner; akin to OHG fano cloth, L pannus cloth, rag] (15c) 1 a: a movable device attached to an elevated object (as a spire) for showing the direction of the wind b: one that is changeable or inconstant
2: a thin flat or curved object that is rotated about an axis by a flow of fluid or that rotates to cause a fluid to flow or that redirects a flow of fluid "the ~s of a windmill"
3: the web or flat expanded part of a feather--see feather illustration
4: a feather fastened to the shaft near the nock of an arrow -- vaned adj