Original: He was known to his contemporaries as Fra Giovanni da Fiesole (Brother John from Fiesole) and by Vasari as Fra Giovanni Angelico (Brother John the Angelic One).
Simplified: People who knew him when he was older called him Fra Giovanni da Fiesole (Brother John from Fiesole). When Giorgio Vasari wrote about him in Lives of the Artists, in the 1500s, he was already known as Fra Giovanni Angelico (Brother Giovanni who is like an Angel).