The most common usage of the word "flail" in English-language countries today is as a verb. When most people use the word, they probably don't know its origin. In fact, The Merriam-Webster Online Dictionary defines "flail" (the verb) thusly: a) ".to strike with or as if with a flail (like arms flailing the water)"; b) ".to move, swing, or beat as if wielding a flail (flailing a club to drive away the insects)." And the definition of "flail" as a verb comes from the root word ("flegel"), a description of the actual medieval historical instrument, "flail," which Merriam-Webster defines: "a hand threshing implement consisting of a wooden handle at the end of which a stouter and shorter stick is so hung as to swing freely.".

             One variation of the flail was the "chain mace," composed of a long chain normally wrapped in leather with a steel ball (not the spiked metal ball like a flail) at the end. .

             According to the Wikipedia online encyclopedia, the medieval flail was a weapon made of "one (or more) spiked metal balls" that were attached to a strong handle with a "hinge or a chain." It was commonly used in Europe from the 13th Century to the 15th Century, Wikipedia's editors report. Also, there is some clarification needed as to the significance for the era; the "knighted class" used swords, and held the sword in much higher esteem than the flail. But the foot soldiers in that era, especially the "Hussites," used the flail as their "national weapon" because swords weren't as powerful while warring on foot as they were while fighting on a horse, like the knighted class of warriors. .

             The medieval flail is "appreciably more damaging than either the sword or the mace," and it doesn't "transfer vibrations from the impact of the wielder" like the sword does. Also, the flail was especially useful when the fighter was up against a sword-wielding soldier who had a shield to protect his body; the flail could "curve over a shield" and also makes it a clumsy defense to protect against a swinging flail.