flail (n.) Look up flail at Dictionary.com
"implement for threshing grain," c.1100, perhaps from an unrecorded Old English *flegel, which probably represents West Germanic *flagil (cognates: 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).
flail (v.) Look up flail at Dictionary.com
15c., from flail (n.); originally "to scourge;" sense of "to move like a flail" is from 1874. Related: Flailed; flailing.