Dipthongs Examples - Softschools A dipthong is the term for a vowel sound that is created by two vowels working together. There is only one sound, but two vowels are used to make the sound. Some describe the sound as a "gliding" from one of the vowels to the other without separating the sound Diphthong Practice List - SpellingCity The sound begins as one vowel sound and moves towards another. The two most common diphthongs in the English language are the letter combination “oy”/“oi”, as in “boy” or “coin”, and “ow”/ “ou”, as in “cloud” or “cow”. Diphthongs are usually introduced as spelling patterns in the primary grades.