The origin of the word Andorra is unknown, although several hypotheses have been formulated. The oldest derivation of the word Andorra is from the Greek historian Polybius (The Histories III, 35, 1) who describes the Andosins, an Iberian Pre-Roman tribe, as historically located in the valleys of Andorra and facing the Carthaginian army in its passage through the Pyrenees during the Punic Wars. The word Andosini or Andosins (Ἀνδοσίνοι) may derive from the Basque handia whose meaning is "big" or "giant". The Andorran toponymy shows evidence of Basque language in the area. Another theory suggests that the word Andorra may derive from the old word Anorra that contains the Basque word ur (water).
Another theory suggests that Andorra may derive from Arabic al-durra, meaning "The forest" (الدرة). When the Arabs and Moors conquered the Iberian Peninsula, the valleys of the High Pyrenees were covered by large tracts of forest, and most of the regions that were not administered by Muslims, because of the geographical difficulty that was presented, received this designation.
Other theories suggest that the term derives from the Navarro-Aragonese andurrial, which means "land covered with bushes" or "scrubland".
The folk etymology holds that Charlemagne had named the region as a reference to the Biblical Canaanite valley of Endor or Andor (where the Midianites had been defeated), a name also bestowed by his heir and son Louis le Debonnaire after defeating the Moors in the "wild valleys of Hell".