Made even more confusing that you can do it with some nationalities but not others. So "a French" is out, but most nationalities ending "-an" are OK: an America

Made even more confusing that you can do it with some nationalities but not others. So "a French" is out, but most nationalities ending "-an" are OK: an American, a German, an Afghan, a Norwegian, a Russian, an Italian. Also "-ese", though with something of an archaic air: a Chinese, a Maltese, a Portugese. Also a Swiss, an Argentine, an Israeli, because why not? And of course pretty much any adjective can be used as a plural noun with the definite article: the French, the Dutch, the beautiful and the damned, the quick and the dead, etc.