tunnel

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An underground or underwater passage.
2. n. A passage through or under a barrier.
3. n. Obsolete The main flue on a chimney.
4. v. To make a tunnel through or under.
5. v. To produce, shape, or dig in the form of tunnel.
6. v. To make a tunnel.

Century Dictionary and Cyclopedia

1. n. The opening of a chimney for the passage of smoke; a flue.
2. n. Hence, figuratively, a nostril.
3. n. A funnel. See funnel, 1.
4. n. A long pipe-like passage made of wire, into which partridges were decoyed.
5. n. A tunnel-net.
6. n. An arched drain.
7. n. A gallery, passage, or roadway beneath the ground, under the bed of a stream, or through a hill or mountain. Tunnels are used in military operations, in mining, in conveying water, and as passageways for vehicles and railway-trains. They are of various construction, according to the character of the soil or rock through which they pass. In soft silt or sand, as in subways beneath a stream, the interior of the tunnel is lined with brickwork, with, in some instances, a shield of plateiron outside the bricks. In soil, soft rock, or qnicksands, heavy masonry lining is sometimes required. In solid rock, a simple excavation is generally sufficient, as in many of the shorter railroad-tunnels. The section of a tunnel is usually a cylindrical or elliptical arch, with sometimes, in soft soils, an inverted arch below. The earlier modern tunnels were excavated by hand-drilling and blasting; but machine-drilling, by means of compressed air, has been brought to great perfection, and the rate of progression has been increased and the cost of excavation reduced. In the Greathead system of tunneling, the tunnel is made by the use of a cylindrical shield driven forward by hydraulic pressure; the excavation is lined with a east-iron shell, and the interspace between the shell and the sides of the excavation is lined with grout forced in by air-pressure. The shell is made of segments bolted together. Silt and mud are forced through doors in the face of the shield, and excavated material is taken out through air-locks in the bulkhead of the tunnel. The longest railroad-tunnel is the St. Gotthard, through the Alps (about 9 miles); the longest in the United States is the Hoosac tunnel, in western Massachusetts (4¾ miles).
8. n. In mining, any level or drift in a mine open at one end, or which may serve for an adit. See adit, 1.
9. n. In zoology, the underground burrow of some animals, when long and tortuous, as of the mole or of the gopher.
10. To form, cut, ordig a tunnel through or under.
11. To form like a tunnel; hollow out in length.
12. To catch in a tunnel-net.
13. To form, cut. or drive a tunnel.

Wiktionary

1. n. An underground or underwater passage.
2. n. A passage through or under some obstacle.
3. n. A hole in the ground made by an animal, a burrow.
4. v. transitive To make a tunnel through or under something, to burrow.
5. v. intransitive To make a tunnel.

GNU Webster's 1913

1. n. A vessel with a broad mouth at one end, and a pipe or tube at the other, for conveying liquor, fluids, etc., into casks, bottles, or other vessels; a funnel.
2. n. The opening of a chimney for the passage of smoke; a flue; a funnel.
3. n. An artificial passage or archway for conducting canals, roads, or railroads under elevated ground, for the formation of roads under rivers or canals, and the construction of sewers, drains, and the like.
4. n. (Mining) 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.
5. v. To form into a tunnel, or funnel, or to form like a tunnel.
6. v. To catch in a tunnel net.
7. v. To make an opening, or a passageway, through or under
8. v. To make a tunnel.

WordNet 3.0

1. n. a passageway through or under something, usually underground (especially one for trains or cars)
2. v. move through by or as by digging
3. v. force a way through
4. n. a hole made by an animal, usually for shelter