tunnel

Concise Oxford English Dictionary © 2008 Oxford University Press:
tunnel/ˈtʌnl/

▶noun

• 1 an artificial underground passage, as built through a hill or under a building or by a burrowing animal.

• 2 a polytunnel.

▶verb (tunnels, tunnelling, tunnelled; US tunnels, tunneling, tunneled)

• 1 dig or force a passage underground or through something.

• 2 Physics (of a particle) pass through a potential barrier.

– derivatives
tunneller noun.

– origin ME (in the senses ‘tunnel-shaped net’ and ‘flue of a chimney’): from OFr. tonel, dimin. of tonne ‘cask’.