While most saints in the English speaking world are known by their English names, some saints are referred to by Latin names and titles.
St. Albert the Great is one of those saints, frequently called "Albertus Magnus" by some philosophy professors.
Pope Benedict XVI provided an excellent summary of his life during a general audience in 2010, and explained the meaning behind his Latin title:
One of the great masters of medieval theology is St Albert the Great. The title "Great" (Magnus), with which he has passed into history indicates the vastness and depth of his teaching, which he combined with holiness of life. However, his contemporaries did not hesitate to attribute to him titles of excellence even then. One of his disciples, Ulric of Strasbourg, called him the "wonder and miracle of our epoch."
Why he is "Magnus"
One of St. Albert's greatest contributions to Western civilization is the reality that faith and science are compatible, even showcasing how scientists can embark on the path of holiness, as Pope Benedict XVI explains:
He still has a lot to teach us. Above all, St Albert shows that there is no opposition between faith and science, despite certain episodes of misunderstanding that have been recorded in history. A man of faith and prayer, as was St. Albert the Great, can serenely foster the study of the natural sciences and progress in knowledge of the micro- and macrocosm, discovering the laws proper to the subject, since all this contributes to fostering thirst for and love of God … St. Albert the Great reminds us that there is friendship between science and faith and that through their vocation to the study of nature, scientists can take an authentic and fascinating path of holiness.
His intellectual contributions, along with his deep devotion to God, help us to understand why St. Albert was truly "Magnus."