Definitions
1.nounA tool used for threshing, consisting of a long handle with a shorter stick attached with a short piece of chain, thong or similar material.
2.nounA weapon which has the (usually spherical) striking part attached to the handle with a flexible joint such as a chain.
3.verbTo beat using a flail or similar implement.
4.verbTo wave or swing vigorously
5.verbTo thresh.
6.verbTo move like a flail."He was flailing wildly, but didn't land a blow."