<p><strong>Noun</strong></p><ul><li>an underground passage.</li><li>a passageway, as for trains or automobiles, through or under an obstruction, as a city, mountain, river, harbor, or the like.</li><li>an approximately horizontal gallery or corridor in a mine.</li><li>the burrow of an animal.</li><li>Dialect: a funnel.</li></ul><p><strong>Verb</strong></p><ul><li>to construct a passageway through or under: to tunnel a mountain.</li><li>to make or excavate (a tunnel or underground passage): to tunnel a passage under a river.</li><li>to move or proceed by or as if by boring a tunnel: The river tunneled its way through the mountain.</li><li>to pierce or hollow out, as with tunnels.</li><li>to make a tunnel or tunnels: to tunnel through the Alps.</li></ul>