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.]
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   1. To form into a tunnel, or funnel, or to form like a
      tunnel; as, to tunnel fibrous plants into nests. --Derham.
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   2. To catch in a tunnel net.
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   3. To make an opening, or a passageway, through or under; as,
      to tunnel a mountain; to tunnel a river.
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