Pappus Syllabification: (Pap·pus)Pronunciation: /ˈpapəs/Definition of Pappus (fl. circa ad 300–350), Greek mathematician; known as Pappus of Alexandria. His Collection of six books (another two are missing) is the principal source of knowledge of the mathematics of his predecessors. Pappus in other Oxford dictionaries Definition of Pappus in the British & World English dictionary