Air vent
An air vent was a conduit that allowed for the passage of air throughout a facility or starship. 

Both the  and Deep Space Station K-7 had the same type of air vents. In 2268, Montgomery Scott suggested that the tribbles James T. Kirk found in the food synthesizer had likely entered the rest of the Enterprise through its air vents, which led Spock and Kirk to realize that the tribbles had likely entered the space station's storage compartments where quadrotriticale was being stored. (, )

In 2368, William T. Riker suggested flooding the air vents in Ten Forward with anesthizine gas to cripple the aliens who had taken control of Data, Deanna Troi, and Miles O'Brien. Geordi La Forge nixed the suggestion, saying Data would not be susceptible, which meant the rescue would fail. ()

In 2375, the Changeling Laas turned himself into plasma energy and disappeared into an air vent before Kira Nerys could stop him. ()
Life support technology