TUNNEL

[noun] [C] - a long passage under or through the earth, esp. one made by peopleIf you drive on the mountain road, you'll go through a lot of tunnels.The tunnel under the Channel is for rail transport only.If someone has tunnel vision, they can only see things which are directly in front of them.(disapproving) To have tunnel vision is also to consider only one part of a problem or situation, or to hold a single opinion rather than having a more general understanding.