Meaning

• A tool used for threshing, consisting of a long handle with a shorter stick attached with a short piece of chain, thong or similar material.

• A weapon which has the (usually spherical) striking part attached to the handle with a flexible joint such as a chain.

Meaning

• To beat using a flail or similar implement.

• To wave or swing vigorously

• To thresh.

• To move like a flail.

  "He was flailing wildly, but didn't land a blow."