An outpost or outpost station was one of several types of remote or frontier-based sites, typically defined as a base or settlement that was usually minimally equipped that was designed for research and defense, or to monitor the sovereignty of a territory's political border.
While studying the Vulcan star charts, Captain Jonathan Archer and Trip Tucker found a remote outpost quite interesting, just a few light years off their current course. T'Pol told them that it was an ancient Vulcan retreat, a monastery at P'Jem. (ENT: "The Andorian Incident")
Following the Earth-Romulan War, Earth established a series of outpost stations, constructed on asteroids and shielded by cast rodinium, in order to guard the Romulan Neutral Zone. (TOS: "Balance of Terror")
In 2313, the Gatherer Penthor-Mul was captured by the Acamarian Internal Security while leading a raid against the weapons supply depot at the Acamarian outpost Tezber. (TNG: "The Vengeance Factor", okudagram)
In 2366, another Acamarian outpost was mentioned in the police records of Penthor-Mul, which was accessible to the crew of the USS Enterprise-D via the Acamarian planetary database (TNG: "The Vengeance Factor", okudagram)
Calder II was the location, in 2370, of an outpost that consisted of a small science station and had limited defensive capabilities. Because Calder II was a Federation outpost, it was defended by Starfleet. The outpost had a type-four deflector shield, which protected it and the surrounding ruins, as well as two phaser banks. (TNG: "Gambit, Part I")
The Son'a had an outpost on Devos II, in 2375, that was the site of a ketracel-white production facility. In that year, Weyoun had Damar send Dominion ships to the outpost to protect it against a possible Federation attack. (DS9: "Penumbra")