This is a noun compound. Adjectives of nationality often act like nouns and form noun compounds with whatever they are attaching to.
As far as I know, this is not always the case. For example, one says isviçreli kızlar and not *isviçreli kızları. Is there a rule for this?
"isviçreli" is always, without exception, an adjective. You can tell this because of the ending :)
Some adjectives of nationality like "çin," "türk," or "italyan" behave differently though.
Right. :) Some Turkish friends of mine have tried to explain this to me, but I just got more confused. In this case, is "Amerikan kızlar daha güzel" a wrong translation?
It would be correct.
To quote my friend Ektoraskan:
"Okay, I've meditated over it for a bit. Here's my conclusion:
The nationality is treated as an adjective ONLY when the next word denotes someone's profession. Ex.: Alman mühendis, İtalyan piyanist, Japon turist, Rus soprano etc.
In other cases, it's treated as a noun. Because the possession is intended. Thus the next word takes the possessive ending. Ex.: İspanyol halkı (public consisting of Spaniards), İngiliz hükümeti (government belonging to the English), Yunan mafyası (mafia consisting of Greeks), Bulgar vatandaşı (compatriot of Bulgarians) etc.
The words "kız" can be used either way without a difference in meaning. Türk kız = Türk kızı.
The words "kadın" and "erkek" are possessivized only if they refer to all the men and women of the nation. Ex.: Türk kadın = a Turkish woman, vs. Türk kadını = The Turkish women.
The word "adam" is never possessivized in this context: Macar adam."
Some turkish men are beautiful too hoo! kivaç tatlituğ...hey america is not only usa!
But why in the previous exercise with Fransız kızlar çok güzeller you don't use kızları?
Duo is kesinlikle a man: these women are more beautiful than you, those women are more beaitiful than others, these comparisons urgh
For a general statement, you do not use the article. İf you are talking about a specific group of American girls, then yes. "The Brazilian girls we met were okay looking, but the American girls were way more beautiful."