1.nounSheet-metal tubing used as a chimney for a stove or furnace.
2.nounA channel for information which is compartmentalized in such a manner that some parties who might be interested in its use or be able to utilize it are restricted from accessing it.
3.verbTo collect or store (information) in a compartmentalized manner, so that some parties who might be interested in its use or be able to utilize it are restricted from accessing it.