Kaldir is a moon of Midr IV.
Kaldir ranks among the coldest terrestrial locations in the Koprulu sector. Its gaseous upper atmosphere repels heat, blocks out most sunlight that might reach the surface and produces flash-freezes that occur with barely a moment's warning, and coincide with immense temperature drops which can kill just as quickly. Ursadons and a species of extremophilic bacteria that serve as their energy source are the only two indigenous life-forms of significance that have been discovered on Kaldir to date.
A protoss expedition came to Kaldir in 2504 to see if its rotation could be altered and its climate improved. Hoping to make the Swarm stronger by evolving a way to deal with extreme cold, Sarah Kerrigan sent Broodmother Nafash to infest Kaldir.
Kerrigan arrived sometime thereafter and collected the essence of an ursadon matriarch to make the zerg resistant to flash-freezes. After Kerrigan awakened Nafash's hive cluster, the Expedition Leader attempted to contact Shakuras and have them send the Golden Armada. However, the zerg took advantage of the flash-freeze storms and destroyed their psi-link spires.
In Old Norse (and its descendants, Icelandic and Faroese), "kaldir" is the masculine plural of the adjective "kaldr" (cold). Hence "kaldir" translates into "cold (ones)".