Low Gothic, also called Imperial Gothic or simply Gothic, is the "official" common language of most of the myriad trillions of human beings in the Imperium of Man, the tongue of its Adepts and Terra. Low Gothic was derived over many millennia from the prior common language used by the human interstellar federation that existed during the Dark Age of Technology and on Terra at the time of the Great Crusade in the late 30th Millennium that is now known as High Gothic.
Low Gothic is the common man's everyday spoken and written language and it is represented for our purposes as twenty-first century English in the Warhammer 40,000 universe, though in fact it would be utterly unintelligible to English-speakers after tens of thousands of Terran years of linguistic drift and hybridisation with other languages. Low Gothic is composed of not only one, but millions of other dialects of the language derived from High Gothic. These dialects developed over the long years of the Age of Strife when all the interstellar colony worlds of humanity were cut off from trade or communication with one another or with the homeworld of Terra by the powerful Warp Storms that preceded the birth of the Chaos God Slaanesh.
It was quite common during the Age of Technology for human worlds to be settled by small communities of "isolationists." These eccentric groups had often found ways to finance their own colonial voyages which often went unrecorded by the authorities. Many such settlements were founded by ethnic minorities attempting to recreate a sense of national identity away from the overpopulated cities of Old Earth. Some of these groups made a deliberate attempt to revive long dead or moribund languages, perceiving them as a source of national identity and communal strength.
Most worlds have been a part of the Imperium for long enough to have adopted Low Gothic as a universal tongue but there are still a great many Feral Worlds on which Imperial Gothic is not spoken. Inevitably, dialects of Gothic differ from world to world and can be mutually unintelligible. Older planets frequently maintain archaic tongues of their own, to the extent that ruling aristocracies might only know enough Low Gothic to swear in. For highly formal matters, the Adeptus Terra use High Gothic, the precursor language of Imperial Gothic. Many Ecclesiarchy rituals, Administratum edicts and Imperial charters use this ancient and venerable language, spoken when the Emperor of Mankind still walked among His people.
- Dark Heresy Core Rulebook (RPG), pg. 249
- Warhammer 40,000: Rogue Trader (1st Edition)