Bourbonbo͞orbôN´ [key], European royal family, originally of France; a cadet branch of the Capetian dynasty. One branch of the Bourbons occupies the modern Spanish throne, and other branches ruled the Two Sicilies and Parma. It takes its name from the now ruined castle of Bourbon, at Bourbon-l'Archambault, Allier dept., which was the seat of a powerful family descended from Adhémar, a noble of the 9th cent.