The Collaborative International Dictionary of English v.0.48:

Lam \Lam\, v. t. [imp. & p. p. Lammed; p. pr. & vb. n.
   Lamming.] [Icel. lemja to beat, or lama to bruise, both fr.
   lami, lama, lame. See Lame.]
   To beat soundly; to thrash. [Obs. or Low] --Beau. & Fl.
   [1913 Webster]