Is there a rule for the creation of adjectives when speaking about nationalities?
I think the asker was talking about whether there are any regular rules about adding the suffixes like '-ish' / '-ese' / '-(i)an' etc. to the nationality adjectives. I'm of the opinion that you should learn them, I mean the most important ones, by heart and then you will see some similarities and differences between them.
Yes, my question about nationalities was as engee30 said, how to apply the suffixes like for example a person from Brasil is a Brasilian, and a person from Peru is a ... Peruvian. But why that change? Thanks a lot.
I think the Peru change is simply pronunciation- 'Peruian' would be very difficult to say as we don't like clusters of vowel sounds. The letter 'v' is used for this- the adjective from the writer Shaw is shavian.
PS- We use Brazil/Brazilian