This is a conlang I made for my paperlegends fic's universe. While it probably will never get used, I am having a lot of fun making it, so here it is!
The Tengarsa is a language of magic – literally. It’s the language used to make chants and ceremonies and spells, as well as being a language of communication for the Druids and just about any other West European sorcerer, and, in turn, their cultural/colonial descendents (i.e. America, as an ex-colony of Britain). Like English is the most widely spoken trade language, Old Tongue is the most widely spoken magic language.
The language has two parts or modes – the part used for “Spellcraft” and the part used for “Conversation”. It’s the same language, but how you use it changes drastically based on whether you’re doing magic or just chatting.
The language is to magic like what math is to science – it was never created, only notated. Humans discovered long ago (and even still continue to discover to this day) certain words have certain affects when applied to magic, much like certain numbers have certain properties when in science.
Proto-Celtic was a type of Vulgar Tengarsa, derived very incorrectly from the actual language of magic (like many other early/Proto- language forms around the world), and all the other languages since then that descended from Proto-Celtic were related heavily to Tengarsa. Today, one can still find many cognates from Tengarsa to Gaelic languages.
The name “Tengarsa” is from “Tenga Arsa”, and literally means “Old Tongue”.