tunnel

A tunnel is an enclosed passageway that goes through earth, rock, or under water so that people or things can move from one place to another. Many tunnels are built for travel, such as roads, railways, and subways, but they are also used for water systems, drainage, mining, and utility lines. Some are short and simple, while others stretch for many miles beneath mountains, rivers, or busy cities. In nature, animals also make tunnels as homes, hiding places, or escape routes.

The word "tunnel" is also used in a figurative sense. To "tunnel" through a task means to keep moving through it in a direct, focused way, especially when the work feels heavy or difficult. This idea connects with "tunnel vision," where someone pays attention to only one thing and misses what is happening around them. Whether it means a passage under the ground, a route carved through stone, or a strong feeling of moving straight toward an end point, the word suggests a path through something that might otherwise block the way.