stovepipe

Short definition from Wiktionary

Noun

1. 1
   Sheet-metal tubing used as a chimney for a stove or furnace.
2. 2
   A channel for information which is compartmentalized in such a manner that some parties who might be interested in its use or able to make use of it are restricted from accessing it.
3. 3
   A stovepipe hat.
4. 4
   A type of malfunction affecting breechloading firearms, where a spent cartridge casing fails to eject completely, instead becoming stuck in the firearm's ejection port, usually oriented vertically or nearly so.
5. 5
   A trench mortar such as the Stokes mortar.

Verb

1. 1
   To collect or store (information) in a compartmentalized manner, so that some parties who might be interested in its use or able to make use of it are restricted from accessing it.
2. 2
   Of a cartridge case, to become wedged vertically in the ejection port of a breechloading firearm, rather than ejecting completely from the weapon.