The reason you can say "an American" has nothing to do with a vowel or not, there are just some demonyms that for some reason can be used like this, and some th

The reason you can say "an American" has nothing to do with a vowel or not, there are just some demonyms that for some reason can be used like this, and some that can't. For example: * German is countable: https://www.oxfordlearnersdictionaries.com/definition/english/german_2 https://www.oxfordlearnersdictionaries.com/definition/englis... * French is uncountable: https://www.oxfordlearnersdictionaries.com/definition/english/french_2 https://www.oxfordlearnersdictionaries.com/definition/englis... * American is countable: https://www.oxfordlearnersdictionaries.com/definition/english/american_1?q=American https://www.oxfordlearnersdictionaries.com/definition/englis... * Spanish is uncountable: https://www.oxfordlearnersdictionaries.com/definition/english/spanish_2 https://www.oxfordlearnersdictionaries.com/definition/englis... But your explanation about why it is correct is bullshit, has nothing to do with "an" vs "a", the English language is just inconsistent as fuck and some demonyms can be used like this and some can't.