Triphthong

In phonetics, a triphthong /ˈtrɪfθɒŋ/ (from Greek τρίφθογγος, "triphthongos", literally "with three sounds," or "with three tones") is a monosyllabic vowel combination involving a quick but smooth movement of the articulator from one vowel quality to another that passes over a third. While "pure" vowels, or monophthongs, are said to have one target articulator position, diphthongs have two, and triphthongs three.

1 Examples
2 See also
3 References

Examples

First segment is the nucleus

English in British Received Pronunciation (monosyllabic triphthongs with R are optionally distinguished from sequences with disyllabic realizations)

[aʊ̯ə̯] as in hour (compare with disyllabic "plougher" [aʊ̯.ə])
[aɪ̯ə̯] as in fire (compare with disyllabic "higher" [aɪ̯.ə])
[ɔɪ̯ə̯] as in "loir" (compare with final disyllabic sequence in "employer" [ɔɪ̯.ə])

As [eɪ̯] and [əʊ̯] become [ɛə̯] and [ɔː] respectively before //r//, all instances of [eɪ̯.ə] and [əʊ̯.ə] are words with the suffix "-er".

Bernese German (a Swiss German dialect):

[iə̯u̯] as in Gieu 'boy'
[yə̯u̯] as in Gfüeu 'feeling'
[uə̯u̯] as in Schueu 'school'
[yə̯i̯] as in Müej 'trouble'

Latvian:

[ie̯a̯] as in tie [ˈtie̯a̯] 'they'
[uo̯a̯] as in ko [ˈkuo̯a̯] 'what'

Northern Austro-Bavarian^[1]:

[ɔu̯ɐ̯] as in /hɔu̯ɐ̯/ (MHG hâr) 'hair', or as in /ɔu̯ɐ̯/ (mhd. ôr) 'ear'
[ɛi̯ə̯] as in /mɛi̯ə̯/ (MHG mêr) 'more'
[ou̯ɐ̯] as in /ʃnou̯ɐ̯/ (MHG snuor) 'cord'
[ei̯ə̯] as in /fei̯ə̯/ (MHG vier) 'four', or as in /ʃnei̯ə̯l/ (MHG snüerelîn) 'small cord'

The Northern Austro-Bavarian triphthongs have evolved from combinations of former long vowels or diphthongs from the Middle High German (MHG) period and vocalized r.

Second segment is the nucleus

Spanish:

[u̯ei̯] as in buey 'ox'
[u̯ai̯] as in Uruguay
[i̯ai̯] as in cambiáis ('you [plural]change')
[i̯ei̯] as in cambiéis ('that you may change')

Romanian:

[i̯au̯] as in iau 'I take'
[e̯au̯] as in rîdeau 'they were laughing'

Vietnamese:

[ɨ̯əɪ̯] as in tươi 'fresh'
[ɨ̯əʊ̯] as in rượu 'alcohol'
[i̯əʊ̯] as in tiêu 'pepper'
[u̯əɪ̯] as in nuôi 'to nourish'
[u̯iʊ̯] as in khuỵu 'to fall on one's knees'

Third segment is the nucleus

Romanian (semivocalic phonemes marked with reversed circumflex accents):

[e̯o̯a] as in pleoape 'eyelids'
[i̯o̯a] as in creioane 'pencils'

References

^ Gütter, Adolf (1971). Nordbairischer Sprachatlas. pp. maps 8 mhd. â, 9 mhd. ô, 11 mhd. ê, 15 mhd. uo, 13 mhd. ie, 14 mhd. üe.