Abbo of Fleury (äbō`, flörē`), Fr. Abbon de Fleury, 945?–1004, French monk at the abbey of Fleury (at present-day Saint-Benoît-sur-Loire, France). Head of the monastery school, he later taught at the abbey in Ramsey, England, and in 988 became abbot at Fleury. He defended his monastery against domination by the high clergy and also served as a diplomat for King Robert II of France. Abbo wrote on grammar, astronomy, mathematics, and philosophy.