Diptonggo is the single combined sound of a patinig (vowel) followed by a malapatinig in a single syllable.
* Patinig: a / e / i / o / u
* Malapatinig: w / y
In the Filipino language, the following are diptonggo:
aw – ex. lugaw (porridge)
ay – ex. kulay (color)
ey – ex. reyna (queen)
iw – ex. sisiw (chick)
iy – ex. kami’y (contraction of kami ay, which means we are; I’ve only ever seen contractions as examples of the /iy/ diptonggo)
oy – ex. baboy (pig)
uy – ex. kasuy (cashew)
What about ew, ow, uw? They are also technically diptonggo but there are no Filipino words (as yet!) that have them in the same syllable.
And that’s a really important distinction: the patinig and malapatinig of a diptonggo have to be in the same syllable, otherwise they aren’t considered diptonggo. For example, uwak (crow) has a /uw/ but the rules of syllabication in Filipino say that when the w (or y) is followed by another vowel, the w (or y) goes with the vowel after it. So the syllables of uwak would be u-wak — the patinig u and the malapatinig w are in different syllables and are therefore not considered a diptonggo.
Another important thing to know is that — unlike in English, where two vowels could form a diphthong — in Filipino, two vowels that appear next to each other are pronounced separately, are considered separate syllables, and therefore can’t be diptonggo. Examples:
Uupo (will sit) – u-u-po – not a diptonggo
Paano (how) – pa-a-no – not a diptonggo
Noo (forehead) – no-o – not a diptonggo
Again: diptonggo = [patinig] + [malapatinig] in the same syllable