# tunnel

Pronunciation: say "TUN-uhl" /ˈtʌn(ə)l/

## Noun

1. An underground or underwater passage, often built for roads, trains, or pedestrians.
   - Simple: A passage built below the ground or under water for people or vehicles to pass through.
   - _Commuters poured into the tunnel during the evening rush._
   - _Engineers spent years boring the rail tunnel through solid rock._
2. A passage made through or under an obstacle that stands in the way.
   - Simple: A path cut through or under something that blocks the way.
   - _Workers carved a tunnel through the rockfall to clear the blocked road._
   - _A narrow tunnel beneath the wall let the sheep pass into the next field._
5. A hole in the ground dug by an animal, also called a burrow.
   - Simple: A hole or passage in the ground dug by an animal.
   - _The fox bolted down the tunnel at the first sound of the hounds._
   - _Earthworms leave tiny tunnels throughout the topsoil._
6. Something that resembles a tunnel in shape or form.
   - Simple: Something shaped like a tunnel, with a long, narrow, hollow space.
   - _The overhanging branches created a leafy tunnel above the footpath._
   - _She felt as if she were staring down a long tunnel of old memories._
7. A wrapper for a network protocol that lets it travel when it would otherwise be unsupported, blocked, or insecure.
   - Simple: A safe path that carries data through a network when the normal way is blocked or unsafe.
   - _Administrators route the blocked traffic through an encrypted tunnel._
   - _The application opens a tunnel so the older data can cross the firewall safely._
10. The opening of a chimney through which smoke passes; a flue.
   - Simple: The open shaft in a chimney that lets smoke rise and escape.
   - _The sweep cleared the tunnel of years of caked soot._
   - _Warm air drew the smoke up the narrow tunnel of the hearth._
11. A vessel with a broad mouth at one end and a narrow pipe at the other, used to pour liquids into casks or bottles; a funnel.
   - Simple: A tool with a wide top and a narrow tube, used to pour liquids into a bottle without spilling.
   - _The brewer guided the ale into the cask with a wide tunnel._
   - _Using a small tunnel, she filled each vial without a single spill._
13. A level passage driven across the rock layers, or at right angles to the mineral veins a miner wants to reach.
   - Simple: A flat passage cut into a mine to reach the rock veins the miners want.
   - _The company drove a new tunnel across the measures to strike the ore vein._
   - _Each morning the crew followed the tunnel to the working face._

## Verb

3. To dig a tunnel through or under the ground.
   - Simple: To dig a long hole through the ground or under something.
   - _The crew will tunnel beneath the harbor over the next two years._
   - _Escapees tunneled under the fence during the long winter nights._
4. To dig a passage through or beneath something; to burrow.
   - Simple: To make a long hole through or under something.
   - _The company plans to tunnel the ridge for a new mountain highway._
   - _Crews tunneled the embankment to install the drainage line._
8. To transmit data through a tunnel, wrapping it so it can cross networks that would block or fail to carry it.
   - Simple: To send data safely through a network by wrapping it inside another connection.
   - _Engineers tunnel the legacy protocol over a modern encrypted link._
   - _The client tunnels all of its requests through a single secure port._
9. Of a particle, to pass through an energy barrier that it could not cross according to classical physics.
   - Simple: To pass straight through a barrier that should block it, as very tiny particles can.
   - _At the atomic scale, electrons tunnel through barriers that classical physics forbids._
   - _Particles occasionally tunnel past energy walls instead of climbing over them._
12. To insert a catheter into a vein in a way that lets it remain in place for long-term use.
   - Simple: To place a thin tube into a vein so it can stay in for a long time.
   - _The surgeon tunneled the catheter beneath the skin before threading it into the vein._
   - _They tunnel the central line so patients can receive treatment for many months._

## Origin

From Middle French 'tonnelle' (net) or 'tonel' (cask), a diminutive of Old French 'tonne' (cask), a word of uncertain origin. It is related to Old English 'tunne' (tun; cask; barrel).

Source: DictionaryAI, https://dictionaryai.com/define/tunnel (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).