an underground passage.

a passageway, as for trains or automobiles, through or under an obstruction, as a city, mountain, river, harbor, or the like.

an approximately horizontal gallery or corridor in a mine.

the burrow of an animal.

Dialect . a funnel.

to construct a passageway through or under

to tunnel a mountain.

to make or excavate (a tunnel or underground passage)

to tunnel a passage under a river.

to move or proceed by or as if by boring a tunnel

The river tunneled its way through the mountain.

to pierce or hollow out, as with tunnels.

to make a tunnel or tunnels

to tunnel through the Alps.

noun

adit , burrow , channel , crawl space , crawlway , crosscut , drift , hole , hole in the wall , mine , passage , pit , shaft , subway , tube , underpass

verb

burrow , excavate , mine , penetrate , sap , scoop out , undermine , adit , bore , conduit , passageway , shaft , subway , tube , underpass