tunnels

noun

1. 1

   An underground or underwater passage.

2. 2

   A passage through or under some obstacle.

3. 3

   A hole in the ground made by an animal, a burrow.

4. 4

   A wrapper for a protocol that cannot otherwise be used because it is unsupported, blocked, or insecure.

5. 5

   A vessel with a broad mouth at one end, a pipe or tube at the other, for conveying liquor, fluids, etc., into casks, bottles, or other vessels; a funnel.

6. 6

   The opening of a chimney for the passage of smoke; a flue.

7. 7

   A level passage driven across the measures, or at right angles to veins which it is desired to reach; distinguished from the drift, or gangway, which is led along the vein when reached by the tunnel.