1) Communication circuit 
In telecommunications, trunking is a method for a system to provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually. This is analogous to the structure of a tree with one trunk and many branches. Examples of this include telephone systems and the VHF radios commonly used by police agen...
A tray or tube for carrying cables.
System of air ducts eg. in mist-blower.
Trunking is a method of switching incoming radio signals between different repeater stations to prevent interference and ensure access to a repeater.
An extruded PVC-U channel used to contain and protect pipes or cables.