The Collaborative International Dictionary of English v.0.48:

Thresh \Thresh\, v. t. & i. [imp. & p. p. Threshed; p. pr. &
   vb. n. Threshing.]
   Same as Thrash.
   [1913 Webster]

         He would thresh, and thereto dike and delve. --Chaucer.
   [1913 Webster]