An enclosed tube or channel for carrying air or gas.

• A pipe that conveys liquids within a system.

An enclosure for routing electrical or data cables.

• A protective passage for conductors.

A bodily tube that carries secretions such as bile or tears.

• A vessel that drains or delivers glandular fluids.

A tube-like cavity in plant tissue for sap or resin.

• A plant vessel that conducts water, sap, or air.

A layer that traps and guides radio or sound waves.

• A refractive channel in the atmosphere or ocean.

To enclose or route through a duct or ducts.

• To channel a flow by using ducts.

Archaic: guidance or direction.

• Archaic: conduct or leading.