Louis the Pious was a ruler during the Carolingian dynasty who reigned from 814-840. As a historical figure, there are several synonyms that one may use to refer to him. Some of the most popular synonyms for Louis the Pious include Louis I, Louis the Fair, Louis the Debonair, and Hludowic. These synonyms were mainly used during the medieval era, but they are still recognized by modern scholars and historians. Louis the Pious was known for his pacifism and religious piety, which earned him the nickname "the Pious". Overall, these synonyms help to capture the essence of this historical figure and his lasting impact on the Carolingian era.