In phonetics, a triphthong (UK: / /,, US: /-/) (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.
Triphthongs are not to be confused with disyllabic sequences of a diphthong followed by a monophthong, as in German Feuer [ˈfɔʏɐ] 'fire', where the final vowel is longer than those found in triphthongs.
Triphthongs that feature close elements that are typically analyzed as /j/ and /w/ in phonology are not listed. For instance, the Polish word łój [wuj] 'tallow' is typically analyzed as /CVC/ - a sequence of a consonant followed by a vowel and another consonant. This is because the palatal approximant is resyllabified in some inflected forms, such as łojami [wɔˈjami] (instr. pl.), and also because /w/ occurs word-finally after a consonant just like /l/ does (compare przemysł [ˈpʂɛmɨsw] 'industry' with Przemyśl [ˈpʂɛmɨɕl] 'Przemyśl'), which means that both of them behave more like consonants than vowels.
On the other hand, [ɪ̯, i̯, ʊ̯, u̯] are not treated as phonetic consonants when they arise from vocalization of /l/, /v/ or /ɡ/ as they do not share almost all of their features with those three.
Bernese German has the following triphthongs:
They have arisen due to the vocalization of /l/ in the syllable coda; compare the last two with Standard German Gefühl [ɡəˈfyːl] and Schule [ˈʃuːlə], the last one with a schwa not present in the Bernese word.
Danish has the following thriphthongs:
In British Received Pronunciation, and most other non-rhotic (r-dropping) varieties of English, monosyllabic triphthongs with R are optionally distinguished from sequences with disyllabic realizations:
As [eɪ̯] and [əʊ̯] become [ɛə̯] and [ɔː] respectively before /r/, most instances of [eɪ̯.ə] and [əʊ̯.ə] are words with the suffix "-er". Other instances are loanwords, such as boa.
[aʊ̯ə̯, aɪ̯ə̯, ɔɪ̯ə̯] are sometimes written with ⟨awə, ajə, ɔjə⟩, or similarly. On Wikipedia, they are not considered to feature the approximants /w/ and /j/, following the analysis adopted by the majority of sources.
The last two are mostly restricted to European Spanish. In Latin American Spanish (which has no distinct vosotros form), the corresponding words are cambian [ˈkambi̯an] and cambien [ˈkambi̯en], with a rising-opening diphthong followed by a nasal stop and initial, rather than final stress. In phonology, [u̯ei̯, u̯ai̯, i̯ai̯, i̯ei̯] are analyzed as a monosyllabic sequence of three vowels: /uei, uai, iai, iei/. In Help:IPA/Spanish, those triphthongs are transcribed ⟨wej, waj, jaj, jej⟩: [ˈbwej], [uɾuˈɣwaj], [kamˈbjajs], [kamˈbjejs]