a bodily passage or tube lined with epithelial cells and conveying a secretion or other substance
"the tear duct was obstructed"
"the alimentary canal"
"poison is released through a channel in the snake's fangs"
a continuous tube formed by a row of elongated cells lacking intervening end walls
"The histology report described the duct as a continuous tube formed by a row of elongated cells lacking intervening end walls."
an enclosed conduit for a fluid
"The water flowed smoothly through the metal duct that ran beneath the floorboards."
a pipe, tube or canal which carries gas or liquid from one place to another
"The plumber installed a new duct to carry hot water throughout the building."
an enclosure or channel for electrical cable runs, telephone cables, or other conductors
"The electrician ran a new power line through the metal duct to connect it to the server room."
In plain English: A duct is a tube that carries air, water, or other things from one place to another.
"The plumber used a metal duct to connect the pipes in the wall."
Usage: Use duct when referring specifically to the enclosed channels that protect and route wires like electricity or data. Do not use it interchangeably with conduit unless you are describing these specific protective enclosures rather than open pipes for fluids.
to enclose in a duct
"The engineer designed a channel specifically to duct hot air from the furnace into the living room."
The word "duct" comes from the Latin verb dūcō, meaning "to lead" or "conduct." It originally referred to something that leads or conducts, such as a channel for water.