English

English was a language.

In Reality Z-25 31-H, it had spread across the Galaxy by the early 21st century, with most aliens learning at least a little English. How and why this had occurred was a mystery given humanity was mostly unaware of the existence of alien life. (PROSE: Nexus Girl's Lament)

In the 925th Universe, the Man in Grey was uncertain that the language he ordinary spoke with Jenny Over-There was actually English until she confirmed it. (PROSE: Annals of the Jen: One Year of Jenny Over-There: The Birthday Toaster)