Background: OK I admit it. I fell in love with diphthong the first time I pronounced it in my mind; the first time I saw it on a page; the first time Spell-checker corrected its spelling! A diphthong is a sound derived from two vowels, starting with one vowel sound, and flowing onto another. For example: the 'oy' sound in 'oil'. The word 'Diphthong' is derived from the Greek word 'diphthongos' which means "having two sounds." I especially like the concept of a pair together, a duo, a couple, but sounding one after the other to create something new - a combined sound, made by sounding the vowels, one after the other, to create a new sound.