flail

noun

• a threshing tool consisting of a wooden staff with a short heavy stick swinging from it.
• a device similar to a flail, used as a weapon or for flogging.
• a machine having a similar action to a flail, used for threshing or slashing: [as modifier]:a flail hedge trimmer

verb

• 1wave or swing wildly: [no object]:his arms flailed as he sought to maintain his balance
• [no object] flounder; struggle uselessly:I was flailing about in the water

• 2 [with object] beat or flog (someone): he escorted them, flailing their shoulders with his cane
• British cut (vegetation) with a flail:the modern practice of flailing hedges every year with mechanical cutters