Lusitanic definitions of "Lusitanic" or "Lusitanian" may include medieval-to-modern Galicia, because the Portuguese people and Galician people share close linguistic and cultural ties, including pre-Roman Celtic ones. Modern Portuguese and the Galician language both derive from medieval Galician-Portuguese, and the term is a cultural classification more than a historic–geographical definition. Although, in Ancient Roman times, the Gallaeci were not part of Lusitania province, what became the Galician-Portuguese language developed from Vulgar Latin in Gallaecia, which comprised what is now Galicia, as well as north Portugal, the center of the development of post-Roman Portuguese culture. Later Portuguese use of the name "Lusitania"
Lusitania "a country of waters", a root word that formerly meant a prince or sovereign governor of a region. Ancient Romans, such as Pliny the Elder ("Natural History", 3.5) and Varro (116 – 27 BC, cited by Pliny), speculated that the name "Lusitania" had Roman origins, as when Pliny says "lusum enim Liberi Patris aut lyssam cum eo bacchantium nomen dedisse Lusitaniae et Pana praefectum eius universae" [Lusitania takes its name from the "Lusus" associated with Bacchus and the "Lyssa" of his Bacchantes, and Pan is its governor]. "Lusus" is usually translated as "game" or "play", while "lyssa" is a borrowing