Merriam-Webster's Collegiate® Dictionary, 11th Edition
DUCT
I. noun see: tow
Date: 1667
a bodily tube or vessel especially when carrying the secretion of a gland,
2. a pipe, tube, or channel that conveys a substance, a pipe or tubular runway for carrying an electric power line, telephone cables, or other conductors, a tube or elongated cavity (as a xylem vessel) in plant tissue, 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, ductal adjective ductless adjective
II. transitive verb
Date: 1936
to enclose in a duct, to convey (as a gas) through a duct