Just another super-cool word I hadn’t heard since I studied phonics in grade school. (Not what happens at the beach with a flip-flop, nor is it a divot in a skimpy piece of underwear.) When two different vowels get combined in a syllable, not a double vowel, mind you, a dipthong will be in play. Believe me, I couldn’t remember why that mattered so I had to look it up.
You get two sounds from the two different vowels – that’s what makes what we grammarians refer to fondly as a “dip.” The global example used is the “oi” in “oil.” You move from one sound to the other as you pronounce “oil.”
Fascinating and riveting as it is, I end the commentary with a reminder that you don’t have to study phonics anymore, and you’ve probably forgotten another cool grammatical term: schwa! We’ll save that for another lesson.