What is the Unstressed vowel in abandoned?

The unstressed vowel in "abandoned" is the "a" in the second syllable, "ban".

Here's why:

* Stress: The word "abandoned" has the stress on the first syllable, "a-".

* Unstressed Vowel: The vowel in the unstressed syllable often becomes reduced or weakened. In this case, the "a" in "ban" is pronounced with a short, neutral sound, similar to the "uh" sound in the word "but".

So, while the word is spelled with an "a", it's pronounced more like "uh-ban-doned".