A diphthong occurs when two vowels are in the same syllable and are pronounced together.
Strong and Weak Vowels
Spanish vowels are defined as strong or weak:
- strong vowels: a / e / o
- weak vowels: i / u
For two vowels to be part of the same syllable, the vowel combination must be one of the following:
weak + weak (i, u + i, u)
Luisa, construir, ciudad, triunfarLuisa, to build, city, to triumph
weak + strong (i, u + a, e, o)
hielo, miedo, guapaice, fear, pretty
strong + weak (a, e, o + i, u)
deuda, aumento, Moisésdebt, rise, Moses
Any other combination of vowels means that the vowels are in separate syllables, see Pronunciation: accents on hiatuses.
How do we accentuate these words if the stress falls on the diphthong?
All words containing diphthongs follow the general rules for accentuation. If the stress is on the syllable with the diphthong, these are the rules:
1. If the combination is weak + weak, we stress the second weak vowel. For example:
2. If the combination is strong + weak or weak + strong, we always stress the strong vowel (a, e, o). For example:
See also Pronunciation: Where to stress a word in Spanish
Want to make sure your Spanish sounds confident?
We’ll map your knowledge and give you free lessons to focus on your
gaps and mistakes. Start your Braimap today »