triphthong

noun

1. A monosyllabic vowel combination usually involving a quick but smooth movement from one vowel to another that passes over a third one.

   “In Lang Belta vowels usually appear preceding or following a consonant (see previous examples), and as of now no occurrence of diphthongs or triphthongs has been attested.”

2. A disyllabic sequence of a vowel, a semivowel, and a vowel.

   “Before moving on to a solution, it may be worth emphasizing that nouns of the صلوه type originally contained a triphthong. […] In addition to evidence from the Safaitic inscriptions, the discovery of the Graeco-Arabic inscription A1 (Al-Jallad and al-Manaser 2015), where the verb ’tw ‘he came’ is written αθαοα /’atawa/, confirms this to be the case for Old Arabic as well.”