Read the dictionary definition of vane. All definitions for this word.
1. the flattened weblike part of a feather consisting of a series of barbs on either side of the shaft
2. flat surface that rotates and pushes against air or water
3. a fin attached to the tail of an arrow, bomb or missile in order to stabilize or guide it
4. mechanical device attached to an elevated structure; rotates freely to show the direction of the wind