Are yams and sweet potatoes the same?
1640s, "course, direction," from Latin ductus "a leading," past participle of ducere "to lead" (see duke (n.)). Anatomical sense is from 1660s. Meaning "conduit, channel" is 1713; that of "air tube in a structure" is from 1884.
A tubular bodily canal or passage, especially one for carrying a glandular secretion such as bile.
ductless duct·less (dŭkt'lĭs)
Lacking a duct, as glands that only secrete internally.