The Collaborative International Dictionary of English v.0.48:

Swingle \Swin"gle\, v. t. [imp. & p. p. Swingled; p. pr. & vb.
   n. Swingling.] [See Swingel.]
   1. To clean, as flax, by beating it with a swingle, so as to
      separate the coarse parts and the woody substance from it;
      to scutch.
      [1913 Webster]

   2. To beat off the tops of without pulling up the roots; --
      said of weeds. [Prov. Eng.] --Forby.
      [1913 Webster]