Another Oddity of Language

So, last night I realized something:  when we say, "an American," we mean an American person.  But we don't say "an English" to mean an English person.

A Canadian, Mexican, Italian, Russian . . . but not a French, Irish, Turkish, Polish.  We say "a Pole."  Or a Swede or a Dane.  We say "a Danish" but that doesn't mean a person.

I think I may have heard people say "a Vietnamese" or "a Japanese" but that sounds rather ignorant to me.

And of course, we don't say "Chinish."  We say "Chinese."