Tunnelling

from The Collaborative International Dictionary of English v.0.48

Tunnel \Tun"nel\, v. t. [imp. & p. p. {Tunneled}
   (t[u^]n"n[e^]ld) or {Tunnelled}; p. pr. & vb. n. {Tunneling}
   or {Tunnelling}.]
   [1913 Webster]
   1. To form into a tunnel, or funnel, or to form like a
      tunnel; as, to tunnel fibrous plants into nests. --Derham.
      [1913 Webster]

   2. To catch in a tunnel net.
      [1913 Webster]

   3. To make an opening, or a passageway, through or under; as,
      to tunnel a mountain; to tunnel a river.
      [1913 Webster]

from The Free On-line Dictionary of Computing (8 July 2008)

tunnelling

   <networking> (US: "tunneling") Encapsulation of {protocol} A
   within protocol B, such that A treats B as though it were a
   {data link layer}.  Tunnelling is used to get data between
   {administrative domains} which use a protocol that is not
   supported by the {internet} connecting those domains.

   (1997-03-26)