The Collaborative International Dictionary of English v.0.48:

Leather \Leath"er\, v. t. [imp. & p. p. Leathered; p. pr. &
   vb. n. Leathering.]
   To beat, as with a thong of leather. [Obs. or Colloq.] --G.
   Eliot.
   [1913 Webster]