Clayton wrote:In the first syllable(ʌnʌt.) there are 2 vowels.
That is not correct
"unut" is 2 syllables.
The whole word unutterable
has 5 syllables:
un | ut | ter | a | ble
Clayton wrote:How is it possible to have two vowels in one syllable. As far as I know there could be clusters of consonants in one syllable but only one vowel.
It's important to distinguish between vowels and vowel SOUNDS. The word "seat", for example, is one syllable with two vowels, but only one vowel sound
Here is the definition of "syllable" from the Apple Dictionary:
syllable (noun): a unit of pronunciation having one vowel sound, with or without surrounding consonants, forming the whole or a part of a word; e.g., there are two syllables in water
and three in inferno
This page about understanding syllables
may also help.