As found on this site: http://www.thefreedictionary.com/vent
1. A means of escape or release from confinement; an outlet: give vent to one's anger.
2. An opening permitting the escape of fumes, a liquid, a gas, or steam.
3. The small hole at the breech of a gun through which the charge is ignited.
On this website, I believe the last portion of the first definition would be the most accurate.
at 10:27 PM on Oct. 17, 2009