Real Dictionary

vent
countable noun: A vent is a hole in something through which air can come in and smoke, gas, or smells can go out.
verb: If you vent your feelings, you express them forcefully.

vent in American English 1
the action of escaping or passing out, or the means or opportunity to do this; issue; outlet
intransitive verb: to be relieved of pressure or discharged by means of a vent
noun: an opening, as in a wall, serving as an outlet for air, smoke, fumes, or the like
transitive verb: to give free play or expression to (an emotion, passion, etc.)

vent in American English 2
a vertical slit in a garment, esp. one put in the back or sides of a coat
to make a vent or vents in
noun: a slit in the back or side of a coat, jacket, or other garment, at the bottom part of a seam

vent in British English 1
noun: a small opening for the passage or escape of fumes, liquids, etc

vent in British English 2
noun: a vertical slit at the back or both sides of a jacket
verb: to make a vent or vents in (a jacket)

vent in the Oil and Gas Industry
noun: A vent is a device used to control the escape of exhaust gases in a process.