tunnel

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An underground or underwater passage.
• noun A passage through or under a barrier such as a mountain.
• noun A tube-shaped structure.
• intransitive verb To make a tunnel through or under.
• intransitive verb To produce, shape, or dig in the form of a tunnel.
• intransitive verb To make a tunnel.

from The Century Dictionary.

• To form, cut, ordig a tunnel through or under.
• To form like a tunnel; hollow out in length.
• To catch in a tunnel-net.
• To form, cut. or drive a tunnel.
• noun The opening of a chimney for the passage of smoke; a flue.
• noun Hence, figuratively, a nostril.
• noun A funnel. See funnel, 1.
• noun A long pipe-like passage made of wire, into which partridges were decoyed.
• noun A tunnel-net.
• noun An arched drain.
• noun A gallery, passage, or roadway beneath the ground, under the bed of a stream, or through a hill or mountain.
• noun In mining, any level or drift in a mine open at one end, or which may serve for an adit. See adit, 1.
• noun In zoology, the underground burrow of some animals, when long and tortuous, as of the mole or of the gopher.

from the GNU version of the Collaborative International Dictionary of English.

• noun 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.
• noun The opening of a chimney for the passage of smoke; a flue; a funnel.
• noun 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.
• noun (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.
• noun (Metal.) the top of a smelting furnace where the materials are put in.
• noun a limekiln in which coal is burned, as distinguished from a flame kiln, in which wood or peat is used.
• noun a net with a wide mouth at one end and narrow at the other.
• noun a pit or shaft sunk from the top of the ground to the level of a tunnel, for drawing up the earth and stones, for ventilation, lighting, and the like.
• transitive verb To form into a tunnel, or funnel, or to form like a tunnel.
• transitive verb To catch in a tunnel net.
• transitive verb To make an opening, or a passageway, through or under
• intransitive verb To make a tunnel.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An underground or underwater passage.
• noun A passage through or under some obstacle.
• noun A hole in the ground made by an animal, a burrow.
• verb transitive To make a tunnel through or under something, to burrow.
• verb intransitive To make a tunnel.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a passageway through or under something, usually underground (especially one for trains or cars)
• verb move through by or as by digging
• verb force a way through
• noun a hole made by an animal, usually for shelter