Born in Codroipo (Udine), he dead in Rome.
Scholar of Latin literature and Latin language (both classical and medieval), lexicographer.
Professor at the Scuola Normale di Pisa (1923-1933).
Editor (From 1933) and director (from 1950 to death) of the "Latinitatis Italicae Medii Aevi inde ab a. CDLXXVI usque ad a. MXXII lexicon imperfectum", a project of the Union académique internationale,
Professor at the University of Naples (1936-1967, retired).
His son is the mediaeval historian Girolamo Arnaldi (born in Pisa, 1929).
