noun

1. a tube, channel, or canal through which a gas or liquid moves
2. a tube in the body for the passage of excretions or secretions a tear duct, bile duct
3. a conducting tubule in plant tissues, esp. one containing resin, latex, etc.
4. a pipe or conduit through which wires or cables are run, air is circulated or exhausted, etc.

Etymology: ML ducta, conduit < L ductus, a leading, conducting, pp. of ducere, to lead < IE base *deuk-, to pull > tow, tug, L dux, leader