Lingua europa is the term used to describe the common language of the lands ruled by Baron Klaus Wulfenbach; the language itself is German. Agatha H. and the Clockwork Princess reveals that the common language of the empire is actually Romanian. Scientists are often also skilled in Latin, Greek, and German. English is the common language for trade, French is the common language for diplomacy, Arabic is the common language of discussion for some mathematics, and Russian is the common language for jokes. Due to her secretarial duties for Tarsus Beetle, Agatha is fluent in them all.