A Duct

1. a pipe, tube or canal which carries gas or liquid from one place to another

Hyponym: air duct

1. 1. an enclosure or channel for electrical cable runs, telephone cables, or other conductorsHyponym: bus duct
   2. (anatomy) a vessel for conveying lymph or glandular secretions such as tears or bileHyponyms: bile duct, cochlear duct, collecting duct, cystic duct, duct of Wirsung, efferent duct, ejaculatory duct, epithelial duct, lacrimal duct, milk duct, Müllerian duct, nasolacrimal duct, pancreatic duct, paramesonephric duct, tear duct, thoracic duct, thyroglossal duct, utriculosaccular duct, Wolffian duct https://en.wikipedia.org/wiki/Duct_(anatomy)
   3. (botany) a tube or elongated cavity (such as a xylem vessel) for conveying water, sap, or air
2. (physics) a layer (as in the atmosphere or the ocean) which occurs under usually abnormal conditions and in which radio or sound waves are confined to a restricted path
3. (obsolete) guidance, direction