AZO, a distinguished professor of civil law in the university of Bologna, and a native of that city. He was the pupil of Joannes Bassianus, who taught at Bologna towards the end of the 12th century, and who was the author of the famous Arbor Actionum. Azo, whose name is sometimes written Azzo and Azzolenus, and who is sometimes described as Azo Soldanus, from the surname of his father, occupied a very important position amongst the gloss-writers, and his Readings (Lcctura) on the Code, which were collected by his pupil, Alexander de Sancto Ægidio, are considered by Savigny, a most competent judge, to be the most valuable of the works of that school which have come down to us.