The title "Duke of Portugal" was historically associated with the nobility in Portugal, particularly during the Middle Ages and the Renaissance. It was often granted to members of the royal family or prominent nobles, signifying their high status and influence within the kingdom. The title played a role in the political landscape of Portugal, especially during times of succession and territorial disputes. The title is most famously linked to the House of Aviz, which ruled Portugal during the 14th to 16th centuries. Although the title is no longer in active use, it remains a significant part of Portugal's noble heritage and history, reflecting the country's rich aristocratic traditions.