The Dacian language was an Indo-European language spoken by the ancient people of Dacia and it is a source of dispute about its origin and characteristics.
While there are almost no written documents in Dacian, we can find much about it from:
- the toponyms and the names of the kings written in Greek and Roman sources.
- the substrata found in current Romanian language, the language that is spoken almost in the all the places Dacians lived.
The Romanian language contains about 200 words with uncertain origin (like brânză=cheese, veveriţă=squirrel etc), some of which have cognates in Albanian. It is thought that they are borrowings from the Dacian language during Roman rule, and are the remains of the Dacian language. If this is true, then Dacian must have been in the same language group with Illyrian languages.
An alternate hypothesis (originally developed by linguist Bogdan Petriceicu-Hasdeu) is that Dacian was in fact a form of Latin, which could explain the quick "romanization" of the Dacians after the Roman Empire occupied a portion of Dacia (albeit only about on one-seventh of Dacian territory and only for 165 years).