1. Forum
  2. >
  3. Topic: Finnish
  4. >
  5. Diphthongs, syllabification, …


Diphthongs, syllabification, and nuclei

Hey all, In the Tips & Notes of Basics 1, it suggests that diphthongs are considered a side-by-side placement of the component vowels. The example is that au = [ɑ] + [u] = [ɑu]. How does this function in syllables? Does the diphthong act as a single unit for syllabification, where [ɑu] is a nucleus? For example, in the word "kaunis", would it syllabify as ['kɑu.nis] or ['kɑ.u.nis] (or something else)? Apologies if this is addressed in later lessons, I'm obviously not very far into the tree. Thanks!

July 3, 2020



Here are the Finnish diphthongs, that is, combinations of two vowel sounds, which form a single unit of syllabification:

  • Group 1 - everything that ends in i: ai-na, meil-lä, soi-tin, puis-to, hy-myil-lä, äi-ti, pör-röi-nen
  • Group 2 - ends in u: kau-nis, seu-raa, viu-lu, ou-to
  • Group 3 - ends in y: ke-veys, sel-viy-ty-ä, käy-dä, pöy-tä
  • Group 4 - "opening" diphthongs: kie-li, suo-mi, p-re-ä

The groups 2 and 3 are covering the same ground, except that group 2 focuses on back vowels and group 3 on front vowels (according to the requirements of vowel harmony). As you can see, double vowels belong in the same syllable (seu-raa) and double consonants in separate syllables (meil-lä). Obviously, compound words do not follow these rules when one part of the compound ends in vowel and the following starts with one.

All other combinations you may encounter are not diphthongs but vowel unions that are split into two syllables and they are particularly common at the end of words:

  • Group 1 - ends in a: ko-me-a, tans-si-a, sei-so-a, istu-a
  • Group 2 - ends in ä: vih-re-ä, mäm-mi-ä, ek-sy-ä, jää-te-lö-ä
  • Group 3 - ends in o: ra-ot, mu-se-o, ra-di-o (but suo-mi is a diphthong)
  • Group 4 - ends in ö: e-li-ö, nä-öt (but p-re-ä is a diphthong)
  • Group 5 - ends in e: ha-en, ko-e, a-lu-e, yh-ty-e, sä-e, säi-lö-en (but kie-li is a diphthong)

The combination does not exist in Standard Finnish.


Suomen kielen diftongit

V a o u e i y ä ö
a aa au ai
o oo ou oi
u uo uu ui
e eu ee ei ey
i iu ie ii iy
y yi yy
ä äi äy ää
ö öi öy öö

! Suomen kielessä on 18 diftongia.


a o u e i
e i y ä ö

ks. Wikipedia (fin) → Fonotaksi


aamu, auto, aina || aa-mu, au-to, ai-na
ooppera, outo, oikein || oop-pe-ra, ou-to, oi-kein
Suomi, uusi, puisto || Suo-mi, uu-si, puis-to
euro, jee, ei, leyhyttää || eu-ro, jee, ei, ley-hyt-tää
tiu, tie, kiitos, vihkiytyä || tiu, tie, kii-tos, vih-kiy-ty-ä
hyi!, tyyni, || hyi, tyy-ni, yö
äiti, täysi, ääni || äi-ti, täy-si, ää-ni
öinen, pöytä, insinööri || öi-nen, pöy-tä, in-si-nöö-ri

ks. = katso
fin (ks. Jukka Korpelan sivu kielikoodeista)
18 = kahdeksantoista [kah-dek-san-tois-ta]


Wow! Thanks for this very detailed answer!

Learn Finnish in just 5 minutes a day. For free.