How do you spell Skein

Available Definitions:
1)  n. - A quantity of yarn, thread, or the like, put up together, after it is taken from the reel, -- usually tied in a sort of knot.
2)  n. - A metallic strengthening band or thimble on the wooden arm of an axle.
3)  n. - A flight of wild fowl (wild geese or the like).