The Collaborative International Dictionary of English v.0.48:

Earth \Earth\, v. t. [imp. & p. p. Earthed; p. pr. & vb. n.
   Earthing.]
   1. To hide, or cause to hide, in the earth; to chase into a
      burrow or den. "The fox is earthed." --Dryden.
      [1913 Webster]

   2. To cover with earth or mold; to inter; to bury; --
      sometimes with up.
      [1913 Webster]

            The miser earths his treasure, and the thief,
            Watching the mole, half beggars him ere noon.
                                                  --Young.
      [1913 Webster]

            Why this in earthing up a carcass?    --R. Blair.
      [1913 Webster]

WordNet (r) 3.0 (2006):

earthing
    n 1: fastening electrical equipment to earth [syn: grounding,
         earthing]