Diphthongization is the process by which a monophthong becomes a diphthong. There are two processes of diphthongization in Ancient Greek, both of which are diachronic (for a general discussion of the phenomenon, see Andersen 1972).  The first results from the intervocalic loss of w, y, or s, which results in hiatus, i.e., two adjacent vowels in distinct syllables. They then fuse together to form one syllable, as…