An exit was a doorway that allowed people to leave a building.
Sometimes the door used as an exit was also used as the entrance.
The way to an exit was often marked by an exit sign. (Star Trek IV: The Voyage Home)
In 2285, after Admiral Kirk walked through the exit door from the Kobayashi Maru training room, he ran into Captain Spock in the hallway, who wished him a happy birthday. (Star Trek II: The Wrath of Khan)
In 2376, Alice described the real Tom Paris, who wished to escape her clutches, saying, "Life throws up a few roadblocks and he heads for the nearest exit." (VOY: "Alice")