Air ducts are an important part of a building's ventilation system. They are used to transport air from one area to another, and can be made of metal, plastic, or other materials. The term 'air duct' is composed of three words: FLUE, VENT, and intake. FLUE is a four-letter word that refers to a pipe or channel for conveying smoke, gas, or steam from a fireplace, furnace, or boiler. VENT is also a four-letter word that means to allow air or gas to escape or enter a space. Intake is a six-letter word that means the act of taking in or absorbing something, such as air. Together, these three words form the term 'air duct, ' which is used to describe a system of pipes or channels used to transport air from one area to another.