Dual Vowel Sound in One Syllable, as in Join, Loud

This page is the CodyCross answer for the clue below from Sense of Smell, Group 1479, Puzzle 3 (Lighter Fuel).

Question is: Dual Vowel Sound in One Syllable, as in Join, Loud

and the answer is: DIPHTHONG

Word Meaning:

DIPHTHONG — (phonology) A complex vowel sound that begins with the sound of one vowel and ends with the sound of another vowel, in the same syllable.

Definitions from Wiktionary.

Dual Vowel Sound In One Syllable, As In Join, Loud - Sense of Smell CodyCross Answers | CodyCross Solutions