Yours, Etc.: Origins and Uses of 8 Sign-Offs
"implement for threshing grain," c.1100, perhaps from an unrecorded Old English *flegel, which probably represents West Germanic *flagil (cf. Middle Dutch and Low German vlegel, Old High German flegel, German flegel), a borrowing of Late Latin flagellum "winnowing tool, flail," from Latin flagellum "whip" (see flagellum).
15c., from flail (n.); originally "to scourge;" sense of "to move like a flail" is from 1874. Related: Flailed; flailing.
v. flailed, flail·ing, flails
To move vigorously or erratically; thrash about.
To strike or lash out violently.
ancient hand tool for threshing grain. It consists of two pieces of wood: the handstaff, or helve, and the beater, joined by a thong. The handstaff is a light rod several feet long, the beater a shorter piece. With a flail, one man could thresh 7 bushels of wheat, 8 of rye, 15 of barley, 18 of oats, or 20 of buckwheat in a day (one bushel equals about 35 litres). The flail remained the principal method of threshing until the mid-19th century, when mechanical threshers became widespread (see thresher).