duct

/dʌkt/
noun
  1. A tube or channel that carries air, liquid, or other substances, especially in a building or machine.
    • The heating duct in the basement needs to be cleaned.
    • Water flows through a duct from the roof to the garden.
    • The air conditioning duct runs behind the walls.
  2. A tube in the body that carries a fluid such as tears, bile, or sweat.
    • A blocked tear duct can cause watery eyes.
    • Sweat glands release sweat through tiny ducts in the skin.
    • The bile duct carries bile from the liver to the small intestine.