This article contains a list of reconstructed words of the ancient Dacian language. They have been restored by some linguists from attested Dacian place and personal names (toponyms and anthroponyms) and from words believed to be Dacian relics in the modern Romanian and Albanian languages.
In the case of words reconstructed from onomastic evidence, the original meanings ascribed to the names in question are derived from examination of closely cognate words and placenames in other Indo-European languages, complemented by analysis of the historical evolution of such placenames. However, the results are hypothetical and subject, in many cases, to divergent etymological interpretations.
Reconstructions derived from Romanian and Albanian words are based on the unproven theory (with some linguists and historians, this theory has become an assumption) that Dacian constitutes the main linguistic substratum of both languages, or the related theory that Dacian and early Albanian both descend from an immediate common ancestor.
Both Georgiev and Duridanov use the comparative linguistic method to decipher ancient Thracian and Dacian names, respectively.
Georgiev argues that one can reliably decipher the meaning of an ancient place-name in an unknown language by comparing it to its successor-names and to cognate place-names and words in other IE languages, both ancient and modern. He gives several examples of his methodology, of which one is summarised here:
The city and river (a tributary of the Danube) in eastern Romania called Cernavodă. In Slavic, the name means "black water". The same town in Antiquity was known as Άξίοπα (Axiopa) or Άξιούπολις (Axioupolis) and its river as the Άξιος (Axios). The working assumption is, therefore, that Axiopa means "black water" in Dacian. According to the known rules of formation of IE composite words, this breaks down as axi = "black" and opa or upa = "water" in Dacian (the -polis element is ignored, as it is a Greek suffix meaning "city"). The assumption is then validated by examining cognate placenames. The axi element is validated by another tributary of the Danube called the Axios, which is today known as Crna reka (located in Republic of Macedonia "black river") and by the older Greek name for the Black sea, Άξεινος πόντος (Axeinos pontos, later altered to the euphemism Euxeinos pontos = "Hospitable sea"). The opa/upa element is validated by the Lithuanian cognate upė ("water"). This etymology is questioned by Russu: Axiopa, a name attested only in Procopius' De Aedificiis, may be a corrupt form of Axiopolis. Even if correct, however, Russu's objection does not invalidate the decipherment of the axi- element.